DE112017001126T5 - Image sensing device - Google Patents

Abstract

An image sensing device (1) comprises: a microlens array (33) having a plurality of micro-condenser lenses (34) disposed at a focus position or focal point of an imaging optical system to be a plurality of upright To produce images of equal magnification; and an imaging unit (31) having photosensitive pixels (32x) disposed at positions corresponding to the micro-condensing lenses (34). The micro-condenser lenses (34) each have a refractive power for focusing, from the light beams incident from the imaging optical system, the light beams incident on positions other than positions at an incident angle within a predetermined limited angle range on which the light rays are incident incident at an incident angle outside the limited angle range. Effective photosensitive areas of the photosensitive pixels (32) receive, of the light beams that have entered the micro-condensing lenses (32), only the light beams incident at an angle of incidence within the limited angular range.

Description

Technical area

The present invention relates to an image capturing device that captures an image formed on a surface of an object, such as a document.

State of the art

As image sensing means for capturing an image by scanning a surface of an object using a one-dimensional imaging member having a plurality of photosensitive pixels arranged in a line shape, there are known imaging sensors called contact image sensors (CISs) become. Contact image sensors find wide applications for image capturing functions of, for example, copiers, image scanners, facsimile machines, or the like. Contact image sensors of these types use an optical element referred to as a rod lens arrangement to produce an upright image with the same magnification, so that there is a problem that the depth of field is small. Therefore, for example, in Patent Literature 1 (Japanese Patent Application Publication JP 1994-342 131 ) discloses a technique for improving the depth of field.

A contact image sensor disclosed in Patent Literature 1 has a plurality of lens elements as an optical element for forming an upright image at the same magnification. In order to improve the depth of focus, an overlap limiting member is disposed on or near an emitting surface of each of the lens elements to limit overlapping of optical images formed by the plurality of lens elements.

Bibliography

patent literature

Patent Literature 1: Japanese Patent Application Publication JP No. 1994-342 131 (for example the 2 and 5 and paragraphs [0015] to [0018]).

Brief description of the invention

Technical problem

In the prior art of Patent Literature 1, since an overlap limiting member is disposed at or near an emitting surface of each of the lens elements, not only the field of view of each of the lens elements is limited, but also the amount of the shielded emission light of FIG each of the lens elements considerably. Therefore, there is a problem that the amount of received light in the one-dimensional imaging element decreases. That is, at an emitting surface of a lens element and in the vicinity thereof, a plurality of light beams which come from points at different object heights in the field of view of the lens element overlap. Therefore, shielding unnecessary beams of light originating from points of large object height in the vicinity of the field of view of the lens element, by the overlap limiting member, inevitably results in shielding of light beams originating from points of low object height near the center of the field of view , Consequently, it is possible that the amount of the received light in the one-dimensional imaging element is unfavorably and considerably reduced.

In view of the foregoing, the object of the present invention is to provide an image sensing device capable of increasing the depth of field while suppressing a decrease in the amount of received light of an imaging element.

Solution to the problem

According to one aspect of the present invention, there is provided an image sensing apparatus comprising: an imaging optical system having N imaging optical elements arranged along a main scanning direction set in advance, where N is an integer greater than or equal 2 wherein each of the N-based optical elements is based on light, the is scattered by a target object, generates an upright image with the same magnification; a microlens array having P micro-condenser lenses arranged along the main scanning direction at focal positions or focal points of the N-imaging optical elements, where P is an integer greater than N; and an imaging unit having P photosensitive pixels or P sets of groups of photosensitive pixels arranged at positions where light beams are concentrated by the microlens array and arranged to correspond to the P micro-condensing lenses, respectively , Each of the micro-condenser lenses has a refractive power such that, of the light beams incident from the imaging optical system, the light beams incident at an angle of incidence within a limited angular range set in advance are concentrated at positions are different from positions incident on the light rays incident at an incident angle outside the limited angle range. The P photosensitive pixels or the P sets of groups of photosensitive pixels have an effective photosensitive area, so that of the main beams passing through the N-imaging optical elements, only the light beams are received at an incident angle within the limited angle range each of the micro-condenser lenses invade.

Advantageous Effects of the Invention

According to the present invention, it is possible to increase the depth of focus while suppressing a decrease in the amount of received light of an imaging element.

list of figures

• 1 Fig. 12 is a perspective view illustrating a schematic configuration of an image sensing device of a first embodiment according to the present invention;
• 2 Fig. 12 schematically illustrates an illustrative image for an imaging performance of a rod lens of the first embodiment;
• 3 Fig. 13 is a diagram schematically illustrating a field of view and an imaging area of a plurality of rod lenses;
• 4 Fig. 12 schematically illustrates an illustrative image for imaging performance of a rod lens in defocusing;
• 5 Fig. 12 schematically illustrates an illustrative image for imaging performance of a rod lens in defocusing;
• 6 Fig. 15 is a perspective view illustrating a schematic configuration of a microlens array and a light-shielding structure of the first embodiment;
• 7 Fig. 12 is a schematic diagram illustrating an example of an essential configuration of an imaging unit of the first embodiment;
• 8A Fig. 12 is a diagram schematically illustrating a rod lens arrangement of the first embodiment;
• 8B FIG. 13 is a diagram illustrating a group of beams propagating toward the rod lens arrangement, and FIG
• 8C Fig. 12 is a diagram schematically illustrating a configuration in the vicinity of an image forming plane where the group of rays arrives;
• 9 Fig. 12 is a diagram schematically illustrating an optical path of a luminous flux incident on a microlens of the first embodiment;
• 10 Fig. 12 is a graph illustrating a relationship between the incident angle of parallel rays incident to a microlens and the concentration position of these parallel light rays;
• 11 Fig. 13 is a diagram schematically illustrating a field of view and an imaging area of a plurality of rod lenses;
• 12A and 12B Fig. 3 are diagrams schematically illustrating optical paths of a luminous flux passing through a rod lens assembly when neither a microlens array nor a light-shielding structure is present;
• 13A and 13B Figs. 10 are diagrams schematically illustrating optical paths of a luminous flux passing through a rod-lens array when a microlens array and a light-shielding structure are present;
• 14 Fig. 12 is a graph illustrating an example of a distribution of an amount of light on an image-forming plane obtained by a simulation calculation;
• 15 Fig. 12 is a graph illustrating another example of a distribution of an amount of light on an image-forming plane obtained by a simulation calculation;
• 16 Fig. 12 is a diagram schematically illustrating an optical path of a luminous flux incident on a microlens of the first embodiment;
• 17 Fig. 15 is a perspective view illustrating a schematic configuration example of a microlens array of a second embodiment according to the present invention;
• 18A Fig. 12 is a diagram illustrating an example of an imaging optical element constituting an imaging optical system of a third embodiment according to the present invention, and Figs
• 18B Fig. 12 is a diagram illustrating an example of the imaging optical system of the third embodiment;
• 19 Fig. 10 is a cross-sectional view illustrating a schematic configuration of an imaging unit of a fourth embodiment according to the present invention;
• 20 Fig. 12 is a schematic diagram illustrating an example of the essential configuration of an imaging unit of the fourth embodiment;
• 21 Fig. 10 is a cross-sectional view schematically illustrating an example of a structure of a light-shielding structure of a fifth embodiment according to the present invention;
• 22 Fig. 12 is a perspective view illustrating a schematic configuration for an image sensing device of a sixth embodiment according to the present invention;
• 23 Fig. 12 is a diagram schematically illustrating a positional relationship between a rod lens assembly, a microlens array, an imaging unit, and a sensor substrate of a sixth embodiment;
• 24 Fig. 10 is a diagram illustrating microlenses and photosensitive pixels of the sixth embodiment;
• 25 Fig. 12 is a diagram illustrating concentration positions on a focal plane of rod lenses of the sixth embodiment;
• 26 Fig. 16 is a graph illustrating a relationship between the angle of incidence of light rays on a microlens and the concentration position;
• 27 Fig. 10 is a diagram illustrating an arrangement of microlenses and photosensitive pixels of the sixth embodiment;
• 28A to 28D Figures are illustrations showing examples of light incident on a microlens;
• 29 Fig. 12 is a graph illustrating an exemplary relationship between the angle of incidence of light rays on a microlens and the concentration position;
• 30 Fig. 12 schematically illustrates an explanatory diagram of an effective photosensitive area of the sixth embodiment;
• 31 Fig. 10 is a block diagram illustrating a schematic configuration of an image signal processor of the sixth embodiment;
• 32 Fig. 10 is a flowchart illustrating an exemplary method of image processing of the sixth embodiment;
• 33 Fig. 10 is a diagram illustrating an example of an image to be captured;
• 34A to 34I are explanatory illustrations of simulation results of image processing;
• 35A to 35D Fig. 10 are explanatory diagrams of an example of image matching processing (step ST3);
• 36 Fig. 10 is a block diagram illustrating a schematic configuration of an image signal processor included in an image sensing device of a seventh embodiment according to the present invention;
• 37 is a flowchart; FIG. 12 illustrates an exemplary method of image processing of the seventh embodiment.

Description of embodiments

Hereinafter, various embodiments according to the present invention will be described with reference to the drawings.

First embodiment

1 Fig. 13 is a perspective view illustrating the essential part of a configuration of an image sensing device 1 a first embodiment according to the present invention schematically represents. As in 1 shown has the image capture device 1 a contact image sensor unit 10 (hereinafter referred to as a "CIS unit 10"), which is an image acquisition unit, and has an image signal processor 40 which generates a signal for the captured image by an output of the CIS unit 10 an image processing is performed. At the target object 2 For example, it is a sheet object such as a paper medium.

The CIS unit 10 indicates: a light source 11 along the main scanning direction x (the lateral direction in 1 ) a line-shaped illumination light LT to a surface to be scanned of the target object 2 emitted; a rod lens arrangement 20 , which is an imaging optical system based on scattered light from the surface of the target to be scanned 2 is reflected and scattered, generates a plurality of upright images with the same magnification; a microlens array 33 at the focus position or focal point of the rod lens assembly 20 is arranged; an imaging unit 31 having a large number of photosensitive pixels by means of the microlens array 33 receive concentrated light; a light-shielding structure (not shown) disposed between the imaging unit 31 and the microlens array 33 is trained; and a sensor substrate 30 , The rod lens arrangement 20 , the sensor substrate 30 , the imaging unit 31 , the microlens arrangement 33 and the light-shielding structure are in a single housing 12 assembled.

The image capture device 1 also includes a scan drive mechanism (not shown) that houses the CIS unit 10 relatively along a sub-scanning direction y orthogonal to the main scanning direction x in relation to the target object 2 shifts. The surface to be scanned of the target object 2 is two-dimensional along the main scanning direction x and the sub-scanning direction y distributed. Therefore, the entire surface to be scanned can be scanned using the CIS unit 10 relatively along the sub-scanning direction y in relation to the target object 2 is moved. It should be noted that the scan drive mechanism is any of a mechanism that incorporates the CIS unit 10 in the sub-scanning direction y relative to the target object 2 shifts, or may be a mechanism that is the target object 2 in the sub-scanning direction y relative to the CIS unit 10 shifts.

As the light source 11 For example, a high-luminescence light source such as a light emitting diode light source, an organic EL (electroluminescent) light source, and a fluorescent tube may be used. In the example of 1 are the light source 11 and the case 12 although they are not intended to be so limited. The light source 11 can be attached to the case 12 to be appropriate.

As in 1 shown, is the light source 11 in relation to the target object 2 on the same page as the rod lens arrangement 20 arranged. In contrast, another light source may be on the opposite side of the target object 2 be arranged so that light passing through the surface of the target object to be scanned 2 is transmitted and scattered, in the rod lens arrangement 20 entry. This makes it possible to realize an image sensing device that generates a captured image based on transmitted scattered light, such as a banknote reader used for ATM (Automated Teller Machines).

In the rod lens arrangement 20 It is an imaging optical system that has a plurality of rod lenses 211 . 212 , ..., 21 _N along the main scanning direction x as an imaging optical elements are arranged. As in 1 1, each of the rod lenses has a cylindrical shape that is orthogonal along the direction of a z-axis in both the main scanning direction x as well as to the sub-scanning direction y extends, and is made of a translucent optical material. Further, each of the rod lenses has the one of the two end surfaces in the longitudinal direction of the rod lens as an incident surface and the other of the two end surfaces as an emitting surface, and generates scattered light propagating in the longitudinal direction from the target object 2 is an upright image of equal magnification on an image-forming plane. Inside each of the rod lenses, a refractive index distribution is formed in which the refractive index continuously changes in the radial direction thereof. By controlling this refractive index distribution, light beams which have entered inside of each of the rod lenses can propagate in the form of a substantially sinusoidal wave along the longitudinal direction. By setting the total length of each of the rod lenses in the direction of the optical axis to an appropriate length, it is possible to produce a rod lens that produces an upright image with the same magnification.

2 Fig. 10 is an explanatory diagram for an image-forming performance of an n-th rod lens 21 _n of the first embodiment schematically. As in 2 As shown, incident light fluxes IL1, IL2 and IL3 propagate from points A1 . A2 and A3 on an object plane OP in the rod lens 21 _n occurred inside the rod lens 21 _n in the form of a substantially sinusoidal wave and are then emitted as luminous fluxes OL1 . OL2 respectively OL3 emitted. Then the emitted luminous fluxes become OL1 . OL2 and OL3 at points B1 . B2 respectively B3 concentrated on an image-forming level IP. In order to produce an upright image with the same magnification, the position of the object plane OP and the image-forming plane IP must be uniquely determined. A distance in the direction of the optical axis between the object plane OP and the incident surface of the rod lens 21 _n be L1 , and a distance in the direction of the optical axis between the emitting surface of the rod lens 21 _n and the image forming level is IP L2 , Here it is necessary that a distance La, for the rod lens 21 _n is specific, satisfies the following expressions: $$\text{L}1=\text{La and L}2=\text{La}\text{,}$$

When these relationships apply, the incident luminous fluxes become IL-1 . IL2 and IL3 on an intermediate image forming plane IMP at an intermediate position in the rod lens 21 _n concentrated. How out 2 As can be seen, an image on the object plane OP is converted to an inverted and reduced intervening image on the intermediate image-forming plane IMP. This intermediate image is further transferred and transferred and generates an inverted enlarged image on the image-forming plane IP. The points B1 . B2 and B3 at the image-forming level IP respectively correspond to the points A1 . A2 and A3 on the object plane OP and are the same distance as the distance of the points A1 . A2 and A3 arranged. Furthermore, the image on the object plane OP by means of the rod lens 21 _n converted into the upright image with the same magnification on the image-forming level IP. A distance from the point A2 to the point A1 be x1 , and a distance from the point B2 to the point B1 be x2 , and the following equation holds: $$\text{x}2/\text{x}1=1.$$

Furthermore, let be an angle of incidence of the principal ray of the incident luminous flux IL-1 that is different from the point A1 from propagates, equal to φ _in , and an emission angle of the main beam of the emitted luminous flux OL1 moving towards the point B1 spread out, be the same φ _out , Here, the following equation (1) applies: $${\mathrm{\phi }}_{\text{in}}={\mathrm{\phi }}_{\text{out}},$$

Such a relationship between the angle of incidence _in and the emission angle φ _out applies in a similar way between the incident luminous flux IL2 and the emitted luminous flux OL2 as well as between the incident luminous flux IL3 and the emitted luminous flux OL3 , As described above, the single rod lens generates 21 _n an upright image of equal magnification on the image-forming plane IP. The rod lens arrangement 20 In the present embodiment, N has rod lenses 211 to 21 _N with the same configuration as the rod lens 21 _n from 2 up in a line along the main scanning direction x are arranged.

3 is an illustration showing the field of view and the imaging area of the rod lens assembly 20 contained rod lenses 21 _n-1 . 21 _n . 21 _{n + 1} and _{21n + 2} schematically represents. In the example of 3 are the microlens arrangement 33 and the light-shielding structure 35 not described later. As in 3 Shown are the rod lenses 21 _n-1 . 21 _n . 21 _{n + 1} and _{21n + 2} fields of view F _n-1 . F _n . Fn _{+ 1} respectively Fn _{+ 2} on. Here, a field of view refers to a region of an object plane OP, the region in which an image on the object plane OP can be transferred to an image-forming plane IP. In addition, the rod lenses form 21 _n-1 . 21 _n . 21 _{n + 1} and _{21n + 2} Areas where an image is transferred to the image-forming plane IP, that is, image-forming areas A _n-1 . A _n . A _{n + 1} or An + 2. Here's a point P1 on the object plane OP in all of the fields of view Fn _-1 . F _n and F _{n + 1} , the rod lenses 21 _n-1 . 21 _n and 21 _{n + 1} Make three dot pictures at the same position Q1 , In this way, a plurality of rod lenses (in particular adjacent rod lenses) in the rod lens arrangement 20 Fields of view that are superimposed on each other, and creates upright images with the same magnification, which are superimposed with each other. Therefore, the plurality of images overlapped by the rod lenses overlap 211 to 21 _N be transmitted on the image-forming level IP and creates an image.

Next, referring to the 4 and 5 the imaging performance of the rod lens 21 _n described at a defocusing. 4 FIG. 13 is a diagram illustrating optical paths in the case where an object plane OP ₁ is formed at a position shifted by -Δz in the direction of a z-axis from an object plane OP in focus, and 5 FIG. 13 is a diagram illustrating optical paths in the case where an object plane OP ₂ is formed at a position shifted by + .DELTA.z in the z-axis direction from the object plane OP in focus. In the examples of 4 and 5 are the microlens arrangement 33 and the light-shielding structure 35 not described later.

• - Punkt Γ1: Da sich die Bildebene IP₂ auf der rechten Seite der bilderzeugenden Ebene IP im Fokus befindet, handelt es sich bei der Vergrößerung (der Transfer-Vergrößerung) des Bilds, das auf der bilderzeugenden Ebene IP erzeugt wird, um eine Verkleinerung.
• - Punkt Σ1: Da sich die bilderzeugende Ebene IP im Fokus auf der rechten Seite der bilderzeugenden Ebene IP₁ befindet, die defokussiert ist, handelt es sich bei einem Bild, das auf der bilderzeugenden Ebene IP erzeugt wird, um ein unscharfes Bild außerhalb des Fokus.

As in 4 represented, generate incident light fluxes IL-1 . IL2 and IL3 that of points A1a . A2a and A3a at the object level OP ₁ out, which is defocused, into the interior of the rod lens 21 _n an intermediate image on an intermediate image-forming plane IMP ₁ inside the rod lens 21 _n and then as the emitted luminous fluxes OL1 . OL2 respectively OL3 emitted. The emitted luminous fluxes OL1 . OL2 and OL3 be on the image-forming level IP ₁ concentrated and then spread to points B1 . B2 and B3 focus on an image-forming IP level. Because the object plane OP ₁ , which is defocused, is formed at a position distant from the object plane OP in focus in the direction of the z-axis by -Δz, is the intermediate image-forming plane IMP ₁ is also formed at a position away in the direction of the negative z-axis on the left side from an intermediate position of the rod lens 21 _n located. It is also an image-forming layer IP ₁ formed at a position on the left side of the image-forming plane IP in focus. When Δz is a small value, the image-forming plane is IP ₁ is formed at a position which is in focus in the z-axis direction by approximately -Δz away from the image-forming plane IP. Because an angle of incidence _in equal to an emission angle φ _out is, becomes an image at the object level OP ₁ , which is defocused and transmitted with upright, even magnification, on an image plane IP ₂ at a position which is in focus in the z-axis direction by + Δz away from the image-forming plane IP. Therefore, the following two points Γ1 and Σ1 are derived.

• - Point Γ1: Since the picture plane IP ₂ On the right side of the image-forming plane IP is in focus, the magnification (transfer magnification) of the image formed on the image-forming plane IP is a reduction.
• Point Σ1: Since the image-forming plane IP is in focus on the right side of the image-forming plane IP ₁ That is, when it is defocused, an image formed on the image-forming plane IP is a blurred image out of focus.

With respect to Γ1, when a distance in the x-axis direction from the point A2a to the point A1a is the same x1a is, the ratio of the distance x2 ( 2 ) to the distance x1a less than 1 as shown in the following inequality: $$\text{x}2/\text{x}1\text{a}=1.$$

When a situation occurs in which the transfer magnification of an image between adjacent rod lenses in the rod lens arrangement occurs 20 is different due to the point Γ1, a positional shift occurs between the images generated by each of the adjacent rod lenses. As a result, a composite image is formed in which two, three or more positional shifts of the image occur. Furthermore, due to the point Σ1, a blurred composite image is generated which is out of focus. Therefore, a means of the entire rod lens arrangement 20 generated image deteriorates.

Here, the degree of deterioration of an image is the case of the dot Γ1 greater than in the case of the point Σ1 , The reason will be explained below. As in 4 Let us now consider a concentration angle (half the angle of a cone) of the emitted luminous flux OL1 that at the point B1 is concentrated, the same θ2 , and an angle of incidence on the image-forming plane IP of the principal ray of the emitted luminous flux OL1 that at the point B1 arrives, be equal θ1 , Assuming that there is a distance between the optical axis of the rod lens 21 _n and the point B1 in the x-axis direction greater than the radius of the rod lens 21 _n is, it can be seen that the angle of incidence θ1 greater than the concentration angle θ2 is, as shown in the following inequality: $$\mathrm{<figure-callout\; id="1"\; label="\theta "\; filenames="DE112017001126T5\_0032.png,DE112017001126T5\_0033.png"\; state="\{\{state\}\}">\theta </figure-callout>}1/\mathrm{\theta }\mathrm{Second}$$

The amount of shift of an image due to the point Γ1 is approximately equal to Δz x θ1, and the radius of a blurred image passing through the point Σ1 is about equal to Δz x θ2. Therefore, the degree of deterioration of an image is in the case of the dot Γ1 greater than in the case of the point Σ1 ,

• - Punkt Γ2: Bei der Vergrößerung (der Transfer-Vergrößerung) eines Bilds, das auf der bilderzeugenden Ebene IP im Fokus erzeugt wird, handelt es sich um eine Vergrößerung zur Vergrößerung.
• - Punkt Σ2: Da sich die bilderzeugende Ebene IP im Fokus auf der linken Seite der bilderzeugenden Ebene IP₂ von 5 befindet, die defokussiert ist, handelt es sich bei einem Bild, das auf der bilderzeugenden Ebene IP erzeugt wird, um ein unscharfes Bild außerhalb des Fokus.

On the other hand, the incident luminous fluxes generate IL-1 . IL2 and IL3 that by points Alb, a2b and A3b at the object level OP ₂ out, which is defocused, into the interior of the rod lens 21 _n have occurred, in the case of defocusing an intermediate image on an intermediate image-forming plane IMP ₂ inside the rod lens 21 _n and then emitted. The emitted luminous flux is at the image-forming level IP ₂ concentrated. In the case of defocusing, which in 5 also conducts a similar investigation as that of the 4 If any of the following points Γ2 and Σ2 from.

• - Point Γ2 : The enlargement (transfer magnification) of an image formed on the image-forming plane IP in focus is an enlargement magnification.
• - Point Σ2 : Because the image-forming level IP is in focus on the left side of the image-forming plane IP ₂ from 5 That is, when it is defocused, an image formed on the image-forming plane IP is a blurred image out of focus.

In the examples of the above-described 4 and 5 are the microlens arrangement 33 and the light-shielding structure 35 not considered. By inserting the microlens array 33 and the light-shielding structure 35 , which will be described later, can be made to disappear a positional shift between images, mainly by the protruding points Γ1 and Γ2 is caused and causes a relatively high degree of image deterioration.

Next is the microlens array 33 and the light-shielding structure 35 described. 6 FIG. 15 is a perspective view showing a schematic configuration of the microlens array. FIG 33 and the light-shielding structure 35 represents.

As in 6 shown, the microlens arrangement 33 a large number of micro-condenser lenses 34 up, along the main scanning direction x are arranged. Each of these micro-condenser lenses 34 (to which also referred to as "microlenses 34 Is referred to) has a lens surface with a cylindrical shape (a cylindrical shape), the on the focus position or the focal point of the rod lenses 211 to 21 _N is arranged. This lens surface faces in the main scanning direction x a positive refractive power with respect to the luminous flux, that of the rod lens arrangement 20 but it points in the sub-scanning direction y no refractive power. Therefore, this lens surface has a non-zero curvature (the reciprocal of the radius of curvature) in the main scanning direction, but points in the sub-scanning direction y no curvature on. Further, the lens surface having the cylindrical shape has an upper portion extending along the sub-scanning direction y extends. A pitch (a pitch) Pt in the main scanning direction x between upper regions of adjacent microlenses 34 and 34 is constant. Furthermore, the microlens arrangement 33 , as in 6 in the z-axis direction, has a constant thickness Ht (that is, the thickness in the z-axis direction between an upper portion of a lens surface of a microlens 34 and the bottom surface of the microlens 34 ). Such a microlens array can be made using a lens material such as a resin or quartz.

The microlens arrangement 33 concentrates one of the rod lens arrangement 20 incident luminous flux to the groups of photosensitive pixels (in 6 not shown) of the imaging unit 31 , The light-shielding structure 35 made of a light-absorbing material is between the imaging unit 31 and the microlens array 33 educated. The light-shielding structure 35 is at the focus position or the focal point of the microlens array 33 arranged and has a function by which a part of the means of the microlens array 33 concentrated light is shielded.

As in 6 shown has the light-shielding structure 35 openings 35s each formed at a position corresponding to each of the upper portions of the microlenses 34 equivalent. Each of these openings 35s is in each case on the optical axes of the microlenses 34 arranged. In addition, each of the openings forms 35s a slot extending along an upper portion of a lens surface of a corresponding microlens 34 extends. Only a part of the microlens arrangement 33 concentrated luminous flux can through the opening 35s through to arrive at a photosensitive pixel. An arrangement pitch of the openings 35s in the main scanning direction x is the same as the arrangement pitch Pt of the upper portions of the microlens 34 , The arrangement pitch of the rod lenses 211 to 21 _N in the main scanning direction x is larger than the arrangement pitch Pt. As will be described later, the light-shielding structure 35 a function on, by the light beams, on the microlens array 33 incident, shielding unnecessary light rays incident at an incident angle greater than or equal to a predetermined critical angle (that is, an angle of incidence outside the limited angular range). Next, a configuration of the imaging unit 31 described. 7 Fig. 12 is a schematic diagram showing an example of the essential configuration of the imaging unit 31 represents.

As in 7 shown, the imaging unit 31 The following: a line sensor 31R for red, the photosensitive pixel 32r which is in a line along the main scanning direction x are arranged on a substrate, a line sensor 31G for green, the photosensitive pixel 32g which is in a line along the main scanning direction x are arranged, as well as a line sensor 31B for blue, the photosensitive pixel 32b which is in a line along the main scanning direction x are arranged. The line sensor 31R for red, the line sensor 31G for green and the line sensor 31B for blue are at the focus position or focal point of the microlens array 33 arranged. The line sensor 31R for red, the line sensor 31G for green and the line sensor 31B for blue can be configured by means of semiconductor imaging elements, such as Complementary Metal-Oxide Semiconductor (CMOS) image sensors or charge-coupled device (CCD) image sensors. The imaging unit 31 also has color filters to produce a color image. That is, the line sensor 31R for red has a red color filter that passes only light in the red wavelength range (a red spectrum), the line sensor 31G for green has a filter that passes only light in the green wavelength range (a green spectrum), and the line sensor 31B for blue has a blue filter that only lets through light in the blue wavelength range (a blue spectrum).

The imaging unit 31 also has peripheral circuits 31A and 31P to analog signal processing on detection outputs of the line sensor 31R for red, the line sensor 31G for green and the line sensor 31B apply to blue on the same substrate. Each of the peripheral circuits 31A may include: a signal processing circuit, such as a control circuit for controlling the operation of the line sensor 31R for red, the line sensor 31G for green and the line sensor 31B for blue, a sample and hold circuit for interrogating and outputting instantaneous values of the detection signals and a signal amplifier circuit. In addition, each of the other peripheral circuits 31P a signal processing circuit for processing analog output signals of the peripheral circuits 31A such as a differential amplifier circuit and an A / D converter.

A peripheral circuit 31P the imaging unit 31 Gives a digital signal, which is obtained as a result of signal processing, over the sensor substrate 30 and a signal transmission path (eg, a cable) in 1 to the image signal processor 40 from. By applying image processing to output signals of the imaging unit 31 can the image signal processor 40 Generate signals for the captured image that form a two-dimensional image on the surface of the target object to be scanned 2 play. A hardware configuration of the image signal processor 40 can be realized by a computer with an integrated central processing unit (CPU). Alternatively, a hardware configuration of the image signal processor 40 by a Large Scale Integrated Circuit (LSI) such as a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC) or a Field Programmable Gate Array (FPGA, Field Programmable gate array).

The imaging unit 31 The present embodiment has three line sensors 31R . 31G and 31B although not limited to them. Instead of the three line sensors 31R . 31G and 31B and the peripheral circuits 31A and 31P which correspond to these, a line sensor and corresponding peripheral circuits can be used.

The configuration of the image sensing device described above 1 will be described in more detail. 8A is an illustration showing the rod lens arrangement 20 schematically represents. In the 8A illustrated rod lens arrangement 20 concentrates a luminous flux propagating from a point An on the object plane OP to a point Bn on the image forming plane IP. The point An and the point Bn are points on the optical axis of the rod lens 21 _n , As with reference to 3 has been described, the rod lens 21 _n and both neighboring rod lenses 21 _n-1 and 21 _{n + 1} the point An in the field of view of the same. As in 8B Therefore, the luminous flux propagating from the point An out, therefore, comprises: a group of rays DL1 moving towards an incident surface of the rod lens 21 _n-1 spread out, a group of rays DL2 moving towards an incident surface of the rod lens 21 _n spread out, as well as a group of rays DL3 Moving towards the incidence surface of the rod lens 21 _{n + 1} spread out. 8C FIG. 13 is a diagram schematically illustrating a configuration of the vicinity of a point Bn on the image-forming plane IP where the groups of rays DL1 . DL2 and DL3 Arrive.

As in 8C is a microlens 34 the microlens array 33 at the focus position or the focal point FP of the rod lens arrangement 20 arranged. The imaging unit 31 is on the sensor substrate 30 arranged. Between a photosensitive pixel 32x (any of the photosensitive pixels 32r . 32g and 32b ) of the imaging unit and the microlens array 33 is the light-shielding structure 35 with an opening 35s formed the photosensitive pixel 32x opposite. An opening 35s the light-shielding structure 35 is formed at such a position that from the groups of the microlens array 33 incident rays DL1 . DL2 and DL3 the group of rays DL2 which is incident at an angle of incidence less than a predetermined critical angle (that is, an angle of incidence within the limited angular range). Therefore, only the group of rays DL2 passing through the rod lens 21 _n through, by means of the microlens 34 concentrated and then enters the photosensitive pixel 32x one. On the other side are the groups of rays DL1 and DL3 through the rod lenses 21 _n-1 and 21 _{n + 1} adjacent to the rod lens 21 _n through the light-shielding structure 35 screened after using the microlens 34 were concentrated. Hence the groups of rays come DL1 and DL3 not on the photosensitive pixel 32x at.

The light-shielding structure 35 is at the focus position or the focal point of the microlens array 33 arranged and can thus shield a part of the light, by means of the microlens array 33 is concentrated. The thickness of the light-shielding structure 35 is compared with the focal length (for example, about 100 μm) of the microlens array 33 sufficiently small (for example, a few microns) to be negligible, and the light-shielding structure 35 and the photosensitive pixels 32x the imaging unit 31 are close to each other. Therefore, it can be said that the effective photosensitive areas (the areas for receiving light used to form a captured image) of the photosensitive pixels 32x essentially at the focus position or focal point of the microlens array 33 are arranged.

9 is an image showing the optical path of one on the microlens 34 schematically represents incident luminous flux OL. Let now be an angle of incidence of the luminous flux OL on the microlens 34 (that is, an angle formed by the luminous flux OL and a normal line of the image-forming plane IP) equals α. The microlens 34 concentrates the luminous flux OL by the positive refractive power at the position of the light-shielding structure 35 , The concentration position (the distance in the main scanning direction x from the central axis of the microlens 34 , that is, from the optical axis) xa is represented by the following equation (2): $$\text{xa}={\text{f}}_{\text{M}}\times \text{tan}\alpha$$

Here are f _M the focal length of the microlenses 34 again.

When parallel light with different angles of incidence α on a microlens 34 is incident on the focal plane of the microlens 34 obtained a distribution of the amount of light corresponding to the angles of incidence α. Assuming that the opening width of an opening 35s in the main scanning direction x ha is the same, therefore, as in 9 shown, only light rays under an absolute value | α | of the incident angle α satisfying the following inequality (3) through the opening 35s through and are from a photosensitive pixel 32x receive: $$\text{tan}\left|\mathrm{\alpha }\right|<\text{Ha}/\left(2\times {\text{f}}_{\text{M}}\right)$$

Because the photosensitive pixel 32x and the opening 35s are close to each other in the z-axis direction, the opening width ha is in the main scanning direction x substantially equal to the width (hereinafter also referred to as "light receiving width") of the effective photosensitive area of the photosensitive pixel 32x , The light-shielding structure 35 is configured to shield from the light rays incident on the microlens array the light rays incident at angles of incidence greater than a critical angle α _L or equal to this satisfying the following equation (3e): $$\text{tan}{\mathrm{\alpha }}_{\text{L}}=\text{Ha}/\left(2\times {\text{f}}_{\text{M}}\right)$$

By the above equation (3e), the critical angle becomes α _L by the following expression ( 3f ): $${\mathrm{\alpha }}_{\text{L}}=\text{arctan}\left[\text{Ha}/\left(2\times {\text{f}}_{\text{M}}\right)\right]$$

Because the photosensitive pixel 32x immediately below the opening 35s is arranged, the light-shielding structure 35 Beams of light that are in the effective photosensitive area of the photosensitive pixel 32x occur on light rays near the central axis of the microlens 34 by shielding the light beams such that the above expression ( 3 ) is satisfied. Therefore, it is possible to obtain an effect similar to the effect of increasing the depth of focus by reducing the aperture in a conventional monocular optical refractive lens system.

• - Punkt P1: Es ist physisch schwierig, eine Blende an der optimalen Position in einer Stablinse einzufügen.
• - Punkt P2: Überlappende Positionen von durch benachbarte Stablinsen überlagerten Bildern sind bei einer Defokussierung zueinander verschoben.

In an optical system for forming an image by superposing a plurality of upright images of the same magnification as a close contact image sensor in the prior art using a rod lens arrangement, it is two points because of the following P1 and P2 difficult to improve the depth of field.

• - Point P1 : It is physically difficult to insert a shutter at the optimum position in a rod lens.
• - Point P2 : Overlapping positions of images superimposed by adjacent rod lenses are displaced relative to each other during defocusing.

In particular, the point P2 represents a problem derived from the difficulty in the prior art to limit the field of view of each of the rod lenses.

In the present embodiment, on the contrary, it is possible to improve the depth of field, which is difficult in the conventional art. Hereinafter, effects of the present embodiment will be given in view of the above-described image deterioration mechanism (FIG. 4 and 5 ) in defocusing in detail.

For the sake of simplicity, it is assumed that the image resolution is equal to 600 dpi (that is, a resolution of 42.3 μm per pixel). Regarding the rod lens arrangement 20 It is believed that the rod lenses 211 to 21 _N , each having a diameter of 0.6 mm, with a pitch of 0.6 mm along the main scanning direction x are arranged. Furthermore, it is assumed that a distance L1 from the object plane OP to the incident surface of the rod lens assembly 20 is equal to 5.1 mm and that a distance L2 from the emitting surface of the rod lens assembly 20 to the image-forming plane IP is also equal to 5.1 mm. It is assumed that each of the rod lenses is in the main scanning direction x a full field of view angle of 20 degrees (a half field angle β = 10 °). That is, light rays entering the rod lens assembly at an angle 20 , which exceeds the range of the angle of incidence of -10 ° to + 10 °, can be in the rod lenses 21 ₁ to 21 _N do not spread. Since for the half field of view angle β = 10 ° L1 = 5.1 mm, the field of view length of a single rod lens on the object plane OP is approximately equal to 1.8 mm (= 2 × 5.1 × tan10 °).

Since the ratio of a field of view length of 1.8 mm to the grid dimension of 0.6 mm of the rod lenses 211 to 21 _N equal 3 In addition, in the case where the microlens array is 33 the present embodiment is absent, as in 3 represented a point on the object plane OP in the field of view of three rod lenses.

Further, it is believed that the microlens array 33 is made of a transparent resin material having, for example, a refractive index of n = 1.59, and that a lens surface of each of the microlenses 34 in the main scanning direction x has a curvature of R = 37 microns. It is believed that the microlenses 34 each a thickness of Ht = 100 μm and with a pitch of Pt = 42.3 μm along the main scanning direction x are arranged.

In this case, a focal length f _M from a microlens 34 calculated as follows: $${\text{f}}_{\text{M}}=\text{R}/\left(\text{n}-1\right)=62.9\mathrm{\mu }\text{m},$$

The focal length in a medium with a refractive index n (= 1.59) is approximately equal to 100 μm (= nxf _M ). Therefore, the parallel luminous flux becomes OL, as in 9 shown on the lower surface of the microlens array 33 focused. The light-shielding structure 35 with the openings 35s is in close contact with the bottom surface of the microlens array 33 arranged. An arrangement pitch Pt of the openings 35s is equal to 42.3 microns. The center of an opening 35s is located on the central axis of each of the microlenses 34 ,

The following describes the effect that the depth of field is increased under the above conditions. 10 Fig. 12 is a graph showing the relationship between the angle of incidence α from parallel to the microlens 34 incident rays and a concentration position xa of these parallel light rays illustrated. This graph was generated using equation (2) above. Since the half field angle β of each of the rod lenses is equal to 10 °, an angle of incidence α is on the microlens 34 incident light rays at the maximum of φ _in = φ _{out of} the above equation (1) is also equal to 10 °. The position at which the light rays with an incident angle of 10 ° on the surface of the light-shielding structure 35 arrive is according to the graphical representation of 10 xa = 11 μm. Thus the light-shielding structure 35 Shielding light rays having a large angle of incidence α, it is necessary here that the opening width ha of the openings 35s satisfies at least the relation of the following inequality (4): $$\text{Ha}/2<\text{xa}$$

That is, it is necessary that the following inequality (5) holds: $$\text{Ha}/2<{\text{f}}_{\text{M}}\times \text{tan}\mathrm{\beta }$$

From the inequality (5) and the above equation (3f), the following inequality (5A) is derived: $${\mathrm{\alpha }}_{\text{L}}=\text{arctan}\left[\text{Ha}/\left(2\times {\text{f}}_{\text{M}}\right)\right]<\mathrm{\beta }$$

Since now ha / 2 = 5 microns and f _M = 62.9 μm is α _L = 4.5 ° and satisfies the inequality (5A). Therefore, run from the light rays entering the rod lens assembly 20 occurred, the light rays incident at an incident angle less than or equal to 10 °, through the rod lens assembly 20 through and enter the microlens array 33 one. Furthermore, by the light rays on the microlens array 33 are incident, the light rays having an angle of incidence within the range of 4.5 ° to 10 °, through a light-shielding portion of the light-shielding structure 35 absorbed, and only the light rays incident at an angle of incidence α of less than 4.5 ° come in the imaging unit 31 at. Therefore, the viewing angle of the rod lens assembly 20 , which originally had the viewing angle of 10 °, by inserting the microlens array 33 and the light-shielding structure 35 between the rod lens arrangement 20 and the imaging unit 31 limited to 4.5 °. This reduces an overlapping area of the field of view between adjacent rod lenses. 11 is an illustration, the fields of view Fn _-1 , Fn, Fn _{+ 1} and Fn _{+ 2} the rod lenses 21 _n-1 . 21 _n . 21 _{n + 1} and _{21n + 2} in the rod lens arrangement 20 included, as well as image-forming areas A _n-1 . A _n . A _{n + 1} and An + 2 schematically represents. A comparison with the in 3 Case shown shows that the overlapping areas of the fields of view Fn _-1 . F _n . Fn _{+ 1} and Fn _{+ 2} due to the presence of the microlens array 33 and the light-shielding structure 35 are narrower.

As described above, the major factor in degrading the depth of focus is the positional shift between images produced by adjacent rod lenses. As the field of view of each of the rod lenses becomes smaller, an incident angle of the outermost light beam on the image-forming plane IP becomes smaller, and a positional shift of an image upon defocus becomes smaller. Therefore, the image capture device 1 of the present embodiment, effectively suppressing deterioration of an image at defocus by adjusting the field of view of the rod lens arrangement 20 is restricted, so that an increase in the depth of field is made possible.

The 12A and 12B are pictures, one of the optical paths through the rod lens arrangement 20 schematically represent passing luminous flux when neither the microlens array 33 still the light-shielding structure 35 available. 12A represents the optical path when focusing, and 12B represents the optical path at defocusing when an object plane OP ₁ is formed at the position which is shifted in the direction of the z-axis by -Δz from the object plane OP in focus. Since each of the rod lenses has a wide field of view when focusing, as in 12A shown, the luminous flux, which falls from a point P on the object plane OP, by three rod lenses in the rod lens assembly 20 and is then concentrated to a point Q on an image-forming plane IP. As in 12B shown, the luminous flux passes from a point Pa on the object plane OP ₁ comes in, with a defocusing by three rod lenses in the rod lens arrangement 20 through and then gets to three points on an image-forming plane IP ₁ concentrated. After that come three rays of luminous flux passing through the image-forming plane IP ₁ have passed through in focus at the image-forming level IP and then arrive at an image plane IP ₂ at a position which is + Δz from the image forming plane IP. In the example of 12B For example, three images are formed on the image-forming plane IP in focus, and since the positions of these three images are considerably shifted from each other, considerable blurring is generated. The extent of the blur φ _a is formed in a region containing the outermost light rays of the three rays of the luminous flux.

On the other side are the 13A and 13B Illustrations, the optical paths of a through the rod lens arrangement 20 schematically represent passing luminous flux when the microlens array 33 and the light-shielding structure 35 available. 13A represents the optical path when focusing, and 13B represents the optical path at defocusing when an object plane OP ₁ is formed at the position which is shifted in the direction of the z-axis by -Δz from the object plane OP in focus. Since each of the rod lenses has a narrow field of view when focusing, as in 13A 2, the luminous flux incident from the point P on the object plane OP passes through a rod lens in the rod lens arrangement 20 and is then concentrated to the point Q on an image-forming plane IP. As in 13B shown, a luminous flux passes from a point Pa on the object plane OP ₁ falls in defocusing by a rod lens in the rod lens arrangement 20 and then gets to a point on an image-forming plane IP ₁ concentrated. After that comes a beam of luminous flux passing through the image-forming plane IP ₁ through at the image-forming level IP in focus and then comes to an image-forming level IP ₂ at a position away from the image-forming plane IP by + Δz. In the example of 13B is the extent of a blur φ _b compared to the extent of the blur φ _a in the case of 12B less, because on the image-forming level IP in focus, an image is generated.

Next, effects of the present embodiment will be described on the basis of a simulation calculation. The 14 and 15 Fig. 11 are graphs illustrating a distribution of a light amount on an image-forming plane obtained by a simulation calculation. In the graphic representations of 14 and 15 The horizontal axis represents the position (unit: mm) from a point (y = 0) on the optical axis of a single rod lens, and the vertical axis represents the amount of the transmitted light. This simulation was carried out in each of the following example and a first and a second comparative example. The amount of transmitted light on the vertical axis in the graphs of 14 and 15 is normalized such that the amount of transmitted light at y = 0 is the same in the case of the first comparative example 1 is.

The example includes a single rod lens, a white surface light source disposed on a focal plane of the rod lens on the object side (the object plane), a microlens array 33 which is arranged on an image-forming plane of the rod lens, an imaging unit 31 near the focus position or focus of the microlens array 33 is arranged, and a light-shielding structure 35 between the imaging unit 31 and the microlens array 33 is arranged. This was an opening 35s used with a slot width of 10 microns.

The first comparative example has a configuration in which the microlens array 33 and the light-shielding structure 35 are removed from the configuration of the example. The second comparative example has a configuration of the first comparative example in which an aperture pf of the aperture is further disposed on an emitting end surface of the rod lens.

The distribution of the amount of light in the graph of 14 represented by a solid line, illustrates a simulation result for the example. The distribution of the amount of light shown in the graphs of the 14 and 15 indicated by broken lines, illustrates a simulation result for the first comparative example, and the distribution of the amount of light shown in the graph of 15 is indicated by a solid line, illustrating a simulation result for the second comparative example. Since a rod lens transmits an image at the same magnification, the width of the distribution of the amount of light reflects the area of the field of view. According to the 14 and 15 becomes clear from the simulation result of the first comparative example, that the original range of the field of view of the rod lens is approximately equal to -1 mm to +1 mm.

According to 14 For example, the area of the field of view of the example has a width of about -0.5 mm to +0.5 mm, and the field of view is limited to about half in comparison with the first comparative example. In addition, it becomes clear that near the optical axis (near y = 0 mm), there is almost no reduction in the amount of light, and the field of view is efficiently limited.

On the other hand, the range of the field of view of the second comparative example differs according to FIG 15 not significantly from the range of the field of view of the first comparative example. In addition, the amount of light is reduced over the entire field of view. This means that placing the aperture of the aperture on the emitting end surface of the rod lens uniformly attenuates only light rays of all image heights, and the effect of limiting the field of view can hardly be achieved.

Next, referring to 16 a configuration is described which avoids interference of light rays between adjacent microlenses 34 and 34 allows. 16 is an illustration showing the optical path of one on the microlenses 34 schematically represents incident luminous flux.

It is assumed that the focal length of a single microlens 34 for example, the same f _M = 300 is μm. Here, an incidence position of the outermost light beam in the half field angle β = 10 ° is equal to xa = f _M x tan = 52 μm. A distance Pt between the adjacent microlenses 34 and 34 is equal to 42.3 microns. Therefore there are cases like in 16 shown in which rays of light on a particular microlens 34 incident on a photosensitive pixel 32x just below the other microlens 34 can arrive, which is adjacent to this, and thereby become stray light, which causes an interference. When such interference occurs, insertion of the microlens array may occur 33 Further, the image may become blurred and may degrade image quality. The condition for preventing such interference is shown in the following inequality (6): $${\text{f}}_{\text{M}}\times \text{tan}\mathrm{\beta }<\text{Pt}-\text{Ha}/2$$

Here, Pt is the arrangement pitch of the microlenses 34 , If Pt = 42.3 μm and ha = 10 μm, the condition is f _M <211 μm required. In fact, it is unlikely that more stray light will occur, if not the outermost beam of light flux directed at a particular microlens 34 think about a boundary between the particular microlens 34 and another, to this adjacent microlens 34 goes out. Therefore, it is more desirable that the condition of the following inequality (7) is satisfied: $${\text{f}}_{\text{M}}\times \text{tan}\mathrm{\beta }<\text{Pt}/2$$

If Pt = 42.3 μm and β = 10 °, the condition becomes f _M <120 μm derived.

As described above, the microlens array is 33 and the light-shielding structure 35 in the image capture device 1 of the first embodiment between the emitting surface of the rod lens assembly 20 and the imaging unit 31 arranged. From the light rays to the microlens array 33 invade, shields the light-shielding structure 35 the rays of light from below an angle of incidence greater than or equal to a critical angle (that is, an angle of incidence outside a limited angular range) and that by means of the microlens array 33 be concentrated. The light-shielding structure 35 does not shield light before it by means of the microlens array 33 is concentrated, but shields light by means of the microlens array 33 was concentrated, and thus the extent of the shielding is low. In addition, an effective photosensitive area of a photosensitive pixel in the imaging unit receives 31 from the light rays on the microlens array 33 only the light incident at a capture angle smaller than the critical angle (that is, an angle of incidence within the limited angular range). Therefore, it is possible to increase the depth of focus while decreasing the amount of received light of the imaging unit 31 is prevented.

Furthermore, an interference of light rays between adjacent microlenses 34 and 34 can be prevented when the comparison expression of the above inequality (6) or (7) is satisfied, and thus the image quality of a captured image can be improved.

Second embodiment

Next, a second embodiment according to the present invention will be described. A lens surface of a micro-condenser lens 34 The first embodiment has only in the main scanning direction x a curvature not equal to zero. A lens surface of a micro-condenser lens of the present embodiment has both in the main scanning direction x as well as in the sub-scanning direction y a curvature not equal to zero. 17 FIG. 15 is a perspective view showing an example of a schematic configuration of a microlens array. FIG 33A represents according to a second embodiment. A configuration of an image sensing device of the present embodiment is the same as that of the image sensing device 1 the first embodiment, except that in 17 shown microlens arrangement 33A instead of the microlens array 33 The first embodiment is included.

As in 17 shown, the microlens arrangement 33A In the present embodiment, three rows of micro-condenser lenses 34A up, along the main scanning direction x are arranged. These micro-condenser lenses 34A (also referred to as "microlenses 34A" hereinafter) include: a row consisting of a group of micro-condenser lenses for impinging incident light on the photosensitive pixels 32r of in 7 shown line sensor 31R focus for red, a series that consists of a group of micro-condenser lenses to direct incident light on the photosensitive pixels 32g of the line sensor 31G for green, as well as a row consisting of a group of micro-condenser lenses for directing incident light onto the photosensitive pixels 32b of the line sensor 31B to focus on blue.

In addition, each of the microlenses exhibits 34A a lens surface which is at the focus position or the focal point of the rod lenses 211 to 21 _N is arranged. This lens surface has a convex shape with a positive power in the main scanning direction x in terms of a luminous flux coming from a rod lens arrangement 20 and also with a positive refractive power in the sub-scanning direction y on. Therefore, the lens surface is in both the main scanning direction x as well as in the sub-scanning direction y a curvature not equal to zero. Examples of a specific curved surface shape of such a microlens 34A have a spherical lens shape with an optical axis passing through the center of a photosensitive pixel 32x (Any of the photosensitive pixels 32r . 32g and 32b ) passes through.

Further, a pitch (a pitch) Pt is in the main scanning direction x between upper regions of adjacent micro-condenser lenses 34A and 34A constant. Furthermore, the microlens arrangement 33A , as in 17 represented, similar to the microlens arrangement 33 of the first embodiment in the z-axis direction has a constant thickness Ht (that is, the thickness in the z-axis direction between an upper portion of a lens surface of a microlens 34A and the bottom surface of the microlens 34A ). Such a microlens arrangement 33A can be made using a lens material such as a resin or quartz.

Because a lens surface of a microlens 34 According to the first embodiment, since the first embodiment has a cylindrical shape, there is an advantage that manufacturing is more problematic than in the lens surface of the present embodiment having a spherical shape. On the other hand, the lens surface of the microlens 34 the first embodiment, a difference in the focal lengths of main scanning x and the sub-scanning direction y and thus there is a difference in the optical path lengths of the main scanning direction x and the sub-scanning direction y in front. If the microlens 34 of the first embodiment, for example, the thickness Ht = 100 μm and the refractive index n = 1.59, a difference in the optical path lengths of the main scanning direction becomes x and the sub-scanning direction y calculated as follows: $$100\mathrm{\mu }\text{m}/\text{n}=62.9\mathrm{\mu }\text{m},$$

Therefore, there is the microlens 34 In the first embodiment, the possibility that the focus positions or the foci between the main scanning direction x and the sub-scanning direction y may differ by 62.9 microns. On the other hand, in the case where a lens surface as in the micro-condenser lens 34A of the present embodiment in the main scanning direction x and the sub-scanning direction y has the same positive refractive power, it is possible to cause the focus positions or focal points in the main scanning direction x and the sub-scanning direction y agree with each other. Therefore, in a defocusing, a better captured image can be generated as compared with the case of the first embodiment.

It is to be noted that it is not always necessary to use a spherical lens, though a spherical lens as a preferable example of the microlens 34A of the present embodiment. An optical lens (for example, an aspherical lens) having a lens shape other than a spherical surface may be used as long as the lens shape allows focus positions or focal points in the main scanning direction x and the sub-scanning direction y agree with each other.

Third embodiment

Next, a third embodiment according to the present invention will be described. The first embodiment is the image capture device 1 of the type with a rod lens arrangement, which the rod lens arrangement 20 is used as an imaging optical system for producing an upright image of the same magnification. The present embodiment is a refractive-lens-array-type image-detecting device comprising a plurality of groups of refractive lenses as a group of imaging optical elements instead of the rod-lens array 20 used. A configuration of the image sensing device of the present embodiment is the same as that of the image sensing device 1 of the first embodiment, except that the plurality of groups of refractive lenses instead of the rod lens arrangement 20 is included.

18A Fig. 13 is an illustration showing an example of an imaging optical element 50 which is included in an imaging optical system of the third embodiment. The imaging optical element 50 has four refractive lenses 51 . 52 . 53 and 54 on. As in 18A 2, a luminous flux incident from a plurality of points on an object plane OP produces an inverted reduced image on an intermediate image forming plane IMP. The imaging optical element 50 generates an upright image of the same magnification on an image-forming plane IP by further enlarging and inverting the inverted reduced image. As in 18B As shown, the imaging optical system of the present embodiment may be arranged by arranging a plurality of such imaging optical elements 50 be configured.

Since the imaging optical system of 18B a plurality of in 18A represented imaging optical elements 50 has generated the plurality of imaging optical elements 50 a plurality of equal magnification upright images superimposed on the image-forming plane IP. The principle of constructing the entire image by superimposing a plurality of upright images at the same magnification in this manner is the same as the principle of the rod lens arrangement 20 ,

Therefore, in the present embodiment, similar to the case of the first embodiment described above, a microlens array is used 33 and a light-shielding structure 35 between an emitting surface of the imaging optical system of 18B and an imaging unit 31 arranged, the field of view of each of the imaging optical elements 50 can be reduced. Therefore, it is possible to increase the depth of focus while decreasing the amount of received light of the imaging unit 31 is prevented. Furthermore, an interference of light rays between adjacent microlenses 34 and 34 can be prevented when the comparison expression of the above inequality (6) or (7) is satisfied, and thus the image quality of a captured image can be improved.

It should be noted that, as can be easily deduced from the above explanation, not only groups of refractive lenses but also reflective concave mirrors may be included as one component as long as the mirrors are a lens array-type imaging optical system that allows upright images to overlap at the same magnification. Also in this case similar effects can be achieved.

Fourth embodiment

Next, a fourth embodiment according to the present invention will be described. In the case of the first embodiment, as in FIGS 8A to 8C is the light-shielding structure 35 formed at a position such that of the groups of beams DL1 . DL2 and DL3 pointing to the microlens arrangement 33 come in, the group of rays DL2 which are incident at an incident angle smaller than the critical angle α _L is. Therefore, only the group of rays DL2 passing through the rod lens 21 _n in 8A through, by means of the microlens 34 concentrated and enters the effective photosensitive area of the photosensitive pixel 32x one. On the other hand, the unnecessary groups of rays become DL1 and DL3 passing through to the rod lens 21 _n neighboring rod lenses 21 _n-1 and 21 _{n + 1} passed through the light-shielding structure 35 screened after using the microlens 34 were concentrated.

In contrast, is 19 a cross-sectional view showing a schematic configuration of an imaging unit 31K of the fourth embodiment. The configuration of an image sensing device of the present embodiment is the same as that of the image sensing device 1 the first embodiment, except that the imaging unit 31K from 19 instead of the light-shielding structure 35 and the imaging unit 31 The first embodiment is included. As in 19 is an effective photosensitive area of a photosensitive pixel 32xa the imaging unit 31K formed over a range in which of the groups of rays DL1 . DL2 and DL3 pointing to the microlens arrangement 33 come in, just a group of rays DL2 which are incident at an incident angle smaller than a critical angle α _L is (that is, an angle of incidence within a limited angular range). Therefore, the groups of rays DL1 and DL3 at an angle of incidence on the microlens array 33 which is greater than the critical angle α _L (that is, an angle of incidence outside the limited angular range) of the photosensitive pixel 32xa not received.

Instead of the light-shielding structure 35 According to the first embodiment, the present embodiment is thus designed to be in the main scanning direction x a lower light-receiving width in the photosensitive pixels 32xa having. Therefore, in a similar manner as in the case of the first embodiment, it is possible to increase the depth of focus while decreasing the amount of received light of the imaging unit 31K is prevented.

Furthermore, in comparison with the imaging unit 31 In the first embodiment, an effect that the dimension of the imaging unit 31K can be reduced. As a manufacturing method for the imaging unit 31K For example, a typical example is a method in which a large number of imaging unit chips are fabricated on a single semiconductor substrate (for example, a silicon wafer) by a semiconductor process, and then this large number of imaging unit chips is separated from each other. Each of the chips for an imaging unit is considered an imaging unit 31K used. A manufacturing process for the imaging unit 31 The first embodiment is also similar to the manufacturing method of the imaging unit 31K , Therefore, as described above, there is an effect that the number of chips for imaging units made of the one semiconductor substrate increases as the light receiving width of the effective photosensitive area of the imaging unit increases 31K becomes smaller and the photosensitive area of the imaging unit 31K gets smaller.

As the dimension of the imaging unit 31K In addition, the size of the entire imaging unit can be small 31K in the sub-scanning direction y be reduced. This point will be described below. 20 Fig. 12 is a schematic diagram showing an example of the essential configuration of the imaging unit 31K of the present embodiment. As in 20 shown, the imaging unit 31K A red line sensor 31Ra having photosensitive pixels 32ra, in a line along the skin scan direction x are arranged on a substrate, a line sensor 31Ga for green, the photosensitive pixel 32ga which is in a line along the main scanning direction x are arranged, as well as a line sensor 31B for blue, the photosensitive pixel 32ba which is in a line along the main scanning direction x are arranged. In the photosensitive pixel 32xa , this in 19 is shown, it is one of the photosensitive pixels 32ra . 32ga and 32ba ,

Furthermore, in the imaging unit 31K peripheral circuits 31A and 31A in an area receiving no light, between the photosensitive pixels 32ra . 32ga and 32ba and the photosensitive pixels 32ra . 32ga and 32ba educated. The function of a peripheral circuit 31A in 20 is similar to the function of the peripheral circuit 31A ( 7 ) of the first embodiment. The imaging unit 31K also has peripheral circuits 31P for processing analog output signals of the peripheral circuits 31A on. The function of a peripheral circuit 31P is similar to the function of the peripheral circuit 31P ( 7 ) of the first embodiment.

Because the peripheral circuits 31A in the fourth embodiment, in the area receiving no light, between the photosensitive pixels 32ra . 32ga and 32ba and the photosensitive pixels 32ra . 32ga and 32ba are formed, is the width H2 the imaging unit 31K in the sub-scanning direction y less than the width H1 ( 7 ) of the imaging unit 31 the first embodiment in the sub-scanning direction y , Therefore, the present embodiment has an effect that the dimension of the imaging unit 31K in the sub-scanning direction y is smaller compared to that of the first embodiment.

The imaging unit 31K The present embodiment has three line sensors 31RA . 31Ga and 31ba although not limited to them. Instead of the three line sensors 31RA . 31Ga and 31ba and the peripheral circuits 31A and 31P , which correspond to these, a line sensor and peripheral circuits can be used, which correspond to this.

Fifth embodiment

Next, a fifth embodiment according to the present invention will be described. 21 FIG. 10 is a cross-sectional view showing an example of a structure of a light-shielding structure. FIG 35A of the fifth embodiment schematically. A configuration of an image sensing device of the present embodiment is the same as that of the image sensing device 1 of the first embodiment, except that the light-shielding structure 35A from 21 instead of the light-shielding structure described above 35 The first embodiment is included.

In 21 the following is shown: two adjacent rod lenses 21 _n and 21 _m (n and m are consecutive integers), a microlens array 33 , the microlenses 34 _n-3 to 34n _{+ 3} and 34m _-3 to 34 _{m + 3} , which at the focus position or the focal point FP of these rod lenses 21 _n and 21 _m are arranged, an imaging unit 31 , the photosensitive pixels 32x at the focal position or focus of the microlens array 33 are arranged, and a light-shielding structure 35A between the imaging unit 31 and the microlens array 33 is arranged. The microlenses 34 _n-3 to 34n _{+ 3} and 34m _-3 to 34 _{m + 3} have the same configuration as that of the above-described microlens 34 of the first embodiment.

The center of an opening 35s the light-shielding structure 35 in the main scanning direction x is in the first embodiment, as in 9 shown on the optical axis of a corresponding microlens 34 arranged. Therefore, the amount of positional shift in the main scanning direction is x between the opening 35s the light-shielding structure 35 and the optical axis of a microlens 34 which corresponds to this, always equal to zero.

The microlenses 34 _n-3 to 34n _{+ 3} are in the present embodiment, as in 21 represented, arranged at positions, that of the rod lens 21 _n on the left side opposite. The main rays Rn-3 to Rn + 3 by the rod lens 21n on the microlenses 34 _n-3 to 34n _{+ 3} invade, each spread to the light-shielding structure 35A out. When the distance from the optical axis OAn of the rod lens 21 _n increases, the angle of incidence of these main rays decreases Rn-3 to Rn + 3 to an image-forming level too. Therefore, the arrival positions of the main rays are different Rn-3 to Rn + 3 on the light-shielding structure 35A from the optical axes of the microlenses 34 _n-3 to 34n _{+ 3} when the incident positions are from the optical axis OAn of the rod lens 21 _n remove. In each case, the extent of a positional shift is coordinated Δn _-3 to Δn _{+ 3} in the main scanning direction x between the centers of openings of the light-shielding structure 35A and the optical axes of the microlenses 34 _n-3 to 34n _{+ 3} specified. The displacement dimensions Δn _-3 to Δn _{+ 3} increase when the openings in the main scanning direction x away from the optical axis OAn of the rod lens 21 _n are located. Because the optical axis of the microlens 34 _n with the optical axis OAn of the rod lens 21 _n is the extent of a positional shift Δ _n between the optical axis of the microlens 34 _n and the center of the opening that corresponds to it, equal to zero.

The microlenses 34m _-3 to 34 _{m + 3} are arranged in a similar manner to positions of the right rod lens 21 _m are opposite. The main rays Rm _-3 to R _{m + 3} on the microlenses 34m _-3 to 34 _{m + 3} come in, each spread from the rod lens 21 _m to the light-shielding structure 35A out. Between the centers of the openings of the light-shielding structure 35A and the optical axes of the microlenses 34m _-3 to 34 _{m + 3} are each dimensions of a positional shift Δm _-3 to Δm _{+ 3} specified. The displacement dimensions Δm _-3 to Δm _{+ 3} increase when the openings in the main scanning direction x away from the optical axis OA _m the rod lens 21 _m are located. Here is the extent of a positional shift Δ _m between the optical axis of the microlens 34 _m and the center of the opening that corresponds to it, equal to zero.

Since the openings of the light-shielding structure 35A As described above, the ratio of the light beams passing through the openings is large with respect to the incident light beams from the rod lenses (hereinafter also referred to as "direct-coverage rod lenses") directly above the respective photosensitive pixels 32x (in the negative direction of the z-axis) are present. Consequently, the distribution of the light beams from the direct-coverage rod lenses is large in an image formed by the imaging unit 31 is won. In addition, a superimposition of images between the adjacent rod lenses 21 _n and 21 _m prevented, so that the depth of field increases in the result.

Further, it is desirable to have the width of the openings of the light-shielding structure 35A to limit and allow the field of view length of each of the rod lenses 21n and 21 _m equal to the arrangement pitch of the rod lenses 21 _n and 21 _m is. This prevents the fields of view of the rod lenses 21 _n and 21 _m between the rod lenses 21 _n and 21 _m overlap, and prevents superimposition of images between the rod lenses 21 _n and 21 _m , In this case, in the case where the central positions of the openings of the light-shielding structure become 35A As is set in the present embodiment so as to coincide with incident positions of the main rays, shading of light rays by the light-shielding structure 35A prevented so that it allows captured images more completely separated between the adjacent rod lenses 21 _n and 21 _m be achieved. As a result, it is possible to obtain a captured image which suppresses deterioration of the depth of field caused by superimposed areas of images between the rod lenses 21 _n and 21 _m is caused.

Sixth embodiment

Next, a sixth embodiment according to the present invention will be described. 22 Fig. 13 is a perspective view illustrating the essential part of a configuration of an image sensing device 1A schematically illustrates a sixth embodiment according to the present invention.

The image capture device A has a contact image sensor unit 10A on (hereinafter referred to as a "CIS unit 10A (Contact Image Sensor unit 10A , Which is an image capturing unit, and has an image signal processor 70 which generates a signal for the captured image by performing image processing on an output of the CIS unit 10A performs, that is, on a raw or unprocessed image signal. A configuration of the CIS unit 10A The present embodiment is the same as that of the CIS unit 10 of the first embodiment, except that an imaging unit 61 from 22 instead of the imaging unit 31 and the light-shielding structure 35 The first embodiment is included. A rod lens arrangement 20 , a sensor substrate 30 , the imaging unit 61 and a microlens array 33 are in a single housing 12A assembled.

Similar to the case of the first embodiment, the image sensing device 1A a scan drive mechanism (not shown) that houses the CIS unit 10A along the sub-scanning direction y relative to a target object 2 shifts that two-dimensionally along the main scanning direction x and the sub-scanning direction y is distributed. Will the CIS unit 10A relative to the target object 2 along the sub-scanning direction y shifted, the entire surface of the target object to be scanned 2 be scanned. It should be noted that the scan drive mechanism is any of a mechanism that incorporates the CIS unit 10A in the sub-scanning direction y relative to the target object 2 shifts, or may be a mechanism that is the target object 2 in the sub-scanning direction y relative to the CIS unit 10A shifts.

The rod lens arrangement 20 has N rod lenses 21 ₁ . 21 ₂ , ... and 21 _N on, the N-imaging optical elements along the main scanning direction x are arranged. These rod lenses 211 . 21 ₂ , ... and 21 _N generate on the basis of light passing through the target object 2 is scattered at the focus positions or focal points (on the incidence surface of the microlens array 33 ) of the rod lenses 211 . 21 ₂ , ... and 21 _N N upright pictures with the same magnification. The microlens arrangement 33 Focuses on the rod lenses 211 to 21 _N incident light rays on groups of photosensitive pixels on the imaging unit 61 ,

23 is an illustration showing a positional relationship between the rod lens arrangement 20 , the microlens arrangement 33 , the imaging unit 61 and the sensor substrate 30 schematically represents. In the example of 23 are rod lenses 21 _n-2 . 21 _n-1 . 21 _n . 21 _{n + 1} and _{21n + 2} (n is an integer), which is in the rod lens arrangement 20 are included along the main scanning direction x arranged. In 23 For the sake of convenience of description, the numbers R = -1, 0 and 1 that the rod lenses _{21n + R} are assigned, using the rod lens 21 _n shown as a reference. For each of the rod lenses _{21n + R} is a lens group arranged thirteen microlenses 34 having, on the optical axis OA _{n + R} the rod lens _{21n + R} is centered. Therefore, in the entire rod lens arrangement 20 microlenses 34 arranged to form N lens groups, each at the focus position or the focal point of each of the N rod lenses 211 to 21 _N is arranged. The number of microlenses 34 which forms each lens group, however, is not limited to thirteen.

As in 24 shown, the imaging unit 61 photosensitive pixels 62 up, along the main scanning direction x are arranged at positions at which light rays by means of the microlenses 34 be concentrated. Similar to the photosensitive pixels 32r . 32g . 32b , ... of the first embodiment, these photosensitive pixels 62 be configured using semiconductor imaging elements, such as CMOS image sensors or CCD image sensors. Each of the photosensitive pixels 62 outputs an analog received signal having an intensity corresponding to the amount of incident light to a peripheral circuit on the imaging unit 61 from. Similar to the peripheral circuits 31A and 31P In the first embodiment, this peripheral circuit performs signal processing on the received analog signal from each of the photosensitive pixels 62 is input to generate a digital received signal and outputs the digital received signal over the sensor substrate 30 and a signal transmission path (for example, a cable) of 22 to the image signal processor 70 from. As will be described in detail later, the image signal processor 70 generate a captured image by using, based on raw or unprocessed image signals, a group of digital received signals received from the imaging unit 61 N field of view images (digital images) are constructed which represent N upright images of the same magnification, by the rod lenses 211 to 21 _N are generated, and these N field of view images are combined.

In the example of 24 is for a microlens 34 a set of photosensitive pixels arranged, containing a set of six photosensitive pixels 62 having. Therefore, each of the thirteen microlenses concentrates 34 attached to each of the rod lenses _{21n + R} is arranged, light beams to thirteen sets of groups of photosensitive pixels out, the total 78 (= 6 x 13 sets) photosensitive pixels 62 exhibit. Groups of photosensitive pixels attached to each of the rod lenses 21 _{n + R} are arranged, can detect a concentrated image by means of the threefold hn microlenses 34 is produced. It should be noted that the number of photosensitive pixels required for a microlens 34 are not specifically limited.

• - Durchmesser Φ von jeder der Stablinsen 21_n+R : 546 µm;
• - Anordnungs-Rastermaß Pr der Stablinsen 211 bis 21_N : 546 µm;
• - halber Sichtfeldwinkel von jeder der Stablinsen 21_n+R : 9°;
• - Anordnungs-Rastermaß in der Hauptabtastrichtung x der Mikrolinsen 34: 42 µm;
• - Krümmungsradius R der zylindrischen Linsenoberflächen der Mikrolinsen 34: 78 µm;
• - Brechungsindex n der Mikrolinsen 34: 1,59; und
• - Dicke der Mikrolinsen 34: 211 µm.

For example, the following example of a configuration is conceivable:

• - Diameter Φ of each of the rod lenses _{21n + R} : 546 μm;
• - Arrangement pitch Pr of rod lenses 211 to 21 _N : 546 μm;
• - Half field of view of each of the rod lenses _{21n + R} : 9 °;
• Arrangement pitch in the main scanning direction x the microlenses 34: 42 μm;
• Radius of curvature R of the cylindrical lens surfaces of the microlenses 34 : 78 μm;
• Refractive index n of the microlenses 34 : 1.59; and
• - Thickness of the microlenses 34 : 211 μm.

In this example of a configuration, the arrangement pitch (= 42 μm) of the microlenses 34 is 1/13 of the pitch Pr of the rod lenses 21 ₁ to 21 _N , 24 represents a state in which parallel beams OL are concentrated at the angle of incidence γ equal to half the field angle ω = 9 ° of each of the rod lenses _{21n + R} is on the microlens 34 come to mind. An arrangement grid of photosensitive pixels 62 in the main scanning direction x is equal to 7 μm. The focal length f _M the microlens 34 is equal to f _M = R / (n - 1 ) = 133 microns. The focal length in a medium with refractive index n is given by nx f _M = 211 μm, and the parallel rays OL can be applied to the lower surface of the microlens 34 after being focused into the microlens 34 occurred.

At the in 24 shown parallel rays OL are rays of light from a point at one end of the field of view on an object via a rod lens _{21n + R} on the microlens 34 come to mind. The light rays OL are by means of the microlens 34 concentrated and become on the lower surface of the microlens 34 focused. The position where the light beams OL are focused is, in this case, one in the main scanning direction x by the following value δ from the optical axis of the microlens 34 distant position, which is the boundary position between the microlenses 34 is: $$\mathrm{\delta }={\text{f}}_{\text{M}}\times \text{tan}\mathrm{\gamma }=21\mathrm{\mu }\text{m},$$

Since there are no light rays incident on the microlens at an angle of incidence exceeding half the field angle ω 34 that will avoid being on the microlens 34 incident light rays interfere with light rays that are incident on the photosensitive pixels 62 on the bottom surface of the other microlenses 34 adjacent to the microlens 34 come to mind.

In the present embodiment, light rays that are incident on a particular microlens interfere 34 come in, and beams of light on other microlenses 34 come in, in the imaging unit 61 not with each other.

As in 9 and in the above equation (2), an image forming position xa varies in the main scanning direction x depending on the angle of incidence α of the light rays on the microlens 34 , Since the angle of incidence α (unit: radians) is a small angle, the above equation (2) can be expressed in the following approximation ( 2a ) being transformed: $$\text{xa}={\text{f}}_{\text{M}}\times \mathrm{\alpha }$$

That is, the image-forming position xa has a linear relationship to the incident angle α. Because six photosensitive pixels 62 are arranged, that of a microlens 34 can match these six photosensitive pixels 62 Receive light rays incident at an incident angle α within the ranges -9 ≦ α ≦ -6 °, -6 ° ≦ α ≦ -3 °, -3 ° ≦ α ≦ 0 °, 0 ≦ α ≦ 3 °, 3 ≦ α ≦ 6 ° or 6 ≤ α <9 °.

As in 25 Meanwhile, a position that is in the main scanning direction is shown x away from the optical axis OAn of the rod lens 21 _n located on the focal plane IP of the rod lens 21 _n (R = 0) denoted by x. On the optical axis OAn, x = 0. The position x is represented by the following expression: $$\text{x}=\text{L}\times \text{tan}\mathrm{\alpha }\mathrm{,}$$

Here L denotes as in 25 illustrated, a distance between an emitting end of the rod lens 21 _n and the focal plane IP. In the case of the above configuration example, L = 5.68 mm.

26 Fig. 12 is a graph showing the relationship between the angle of incidence α of the light rays on the microlens 34 and the concentration position x with respect to the main beam which has passed through the rod lens 21n (R = 0). In this graph, the horizontal axis gives the position x again (unit: mm), while the vertical axis represents the angle of incidence α (unit: °). As in 26 indicated by a solid line indicate the position x and the incident angle α has a substantially linear relationship, and the incident angle α is in a range of -9 ° to + 9 °, and thus the position is x in a range of -0.9 mm to +0.9 mm, that is, within the range of about 3.3 times the pitch Pr (= 546 μm) of the rod lenses 21 ₁ to 21 _N (within a range equivalent to about 3.3 rod lenses).

27 Fig. 12 is a schematic diagram illustrating an example of microlens groups and groups of photosensitive pixels taken along the main scanning direction x being arranged on the optical axis OAn of the n-th rod lens 21 _n are centered. In 27 is a reference numeral 34 _{n, m} a microlens 34 assigned according to the nth rod lens 21 _n is arranged. A reference number 34 _{n, 0} is a microlens 34 assigned, which is arranged on the optical axis OAn. Is m> 0 , denotes a microlens 34 _{n, m} microlenses 34 moving in the negative direction in the main scanning direction x away from the central microlens 3 4 _{n, 0} are located. Is m < 0 , denotes a microlens 34 _{n, m} microlenses 34 moving in the positive direction in the main scanning direction x away from the central microlens 34 _{n, 0} are located. A reference number 34 _{n + 1, m} is a microlens 34 assigned corresponding to one (n + 1) th rod lens 21 _{n + 1} is arranged, and a reference numeral 3 4 _{n-1, m} is a microlens 34 allocated according to a (n- 1 ) -th rod lens 21 _n-1 is arranged. Furthermore, s = 0 . 1 . 2 . 3 . 4 and 5 six photosensitive pixels 62 . 62 . 62 . 62 . 62 respectively 62 assigned corresponding to each of the microlenses 34 are arranged. An integer p is a digit, that of a microlens 34 is assigned, wherein the microlens 34 _{n, 0} on the optical axis OAn of the rod lens 21 _n is used as a reference (p = 0). Unlike the number m, this number p is the microlenses 34 beyond the border between the rod lenses 21 _n and 21 _{n + 1} and the border between the rod lenses 21 _n and 21 _n-1 assigned.

In the case of the above configuration example, photosensitive pixels to which light rays are incident are those through the rod lens 21 _n (R = 0 ), any of six photosensitive pixels directly under the microlenses 34 in that area x = -0.9 mm to +0.9 mm ( 26 ). The 28A to 28D are pictures that schematically represent light rays that are on the microlenses 34 _{n, 0} . 34 _{n, 3} and 34 _{n, 6} come to mind.

In addition, light rays are distributed through the rod lens 21 _n (R = 0 ) and into the microlens 34 _{n, 0} have occurred in the case of the above configuration example over a range of - 2 , 75 ° to + 2.75 ° around an angle of incidence of θ = 0 °. Here, the light rays come to the photosensitive pixels 62 . 62 with s = 2 . 3 on, as in 28A shown schematically, but do not come to the photosensitive pixels with s = 0, 1 . 4 . 5 at. Beams of light through the rod lens 21 _n (R = 0) have passed through and into the microlens 34 _{n, 3} have spread over a range of 2 , 75 ° to + 2.75 ° by an angle of incidence of 12 , 7 ° around. Here, the light rays come to the photosensitive pixels 62 . 62 . 62 with s = 2 . 3 . 4 on, as in 28B shown schematically. Furthermore, the light rays are distributed through the rod lens 21n (R = 0 ) and into the microlens 34 _{n, 6} occurred over a range of - 2 , 75 ° to + 2.75 ° by an angle of incidence of 2 , 54 ° around. Most of the light rays come from the photosensitive pixels 62 . 62 with s = 3, 4 on, as in 28C shown schematically, while a small portion of the light rays on the photosensitive pixel 62 arrives with s = 2.

In this way, the angle of incidence of the light rays on a microlens 34 to act on continuous values while the photosensitive surface on the lower surface of the microlens 34 through six photosensitive pixels 62 in 6 Segments is divided. Therefore, photosensitive pixels are on the photosensitive surface in a mixed manner 62 on which the light rays are incident, only by a rod lens 21 _n through, as well as photosensitive pixels 62 present on which the light rays are incident by several adjacent rod lenses 21 _n-1 and 21 _{n + 1} passed through. 28D is, for example, an image in which the light rays from the adjacent rod lenses 21 _n-1 and 21 _{n + 1} (R = -1, R = +1) to those of the rod lens 21 _n with R = 0 of 28A to be added. In this case, most of the light beams arriving at the photosensitive pixel at s = 3 are light rays from the rod lens 21 _n arrive with R = 0, and also become rays of light through the rod lens 21 _n-1 with R = -1 passed through, mixed in a bit. In the case of the photosensitive pixel with s = 4, only light rays arrive through the rod lens 21 _n-1 with R = -1 passed through. For most of the light rays that occur at the photosensitive pixel with s = 5 arrive are the rays of light through the rod lens 21 _n-1 with R = -1, and also light rays coming from the rod lens 21 _n-2 (not shown) arrive with R = -2, added a little.

Are made of the plurality of photosensitive pixels on the lower surface of the microlenses 34 only the photosensitive pixels 62 When the light beams that have passed through a single rod lens occupy the majority, this allows the construction of a digital image representing an image produced by a single rod lens.

There is a possibility that light rays passing through any of seven rod lenses 21 _n-3 . 21 _n-2 . 21 _n-1 . 21 _n . 21 _{n + 1} . _{21n + 2} . _{21n + 3} (R = -3 to +3), arrive at a group of photosensitive pixels in the range of x = -1.092 mm to +1.092 mm, which is the width of four rod lenses. 29 Fig. 12 is a graph showing an example of the relationship between the angle of incidence α and the concentration position of the microlenses 34 incident light rays with respect to the light rays illustrated by the seven rod lenses 21 _n-3 to _{21n + 3} (R = -3 to +3) have passed through. According to 29 it becomes clear that for the example x = 0, a luminous flux with the main ray α = 0 ° from the rod lens 21 _n (R = 0) ago, a luminous flux with the main beam α = 5.5 ° from the rod lens 21 _n-1 (R = -1) ago and a luminous flux with the main beam α = -5.5 ° from the rod lens 21 _{n + 1} (R = +1) ago.

For each of the rod lenses 21 _n For example, on photosensitive surfaces of a group of photosensitive pixels of the present embodiment, effective photosensitive areas are set so as to be separated from the main beams by a rod lens 21n have passed through only receiving the light rays which are incident at an angle of incidence α within a limited angular range to a microlens 34 _{n, m} come to mind. For each of the microlenses 34 _{n, m} is an effective photosensitive area set. Assuming that it is α ₁ and α ₂ by angles of incidence of light rays on a microlens 34 _{n, m} and critical angles which define the upper limit and the lower limit of the limited angular range, respectively, the limited angular range can be determined using the critical angles α ₁ and α ₂ are represented by the following inequality, wherein α ₁ and α ₂ equals a positive or a negative value are: $${\mathrm{\alpha }}_1<\mathrm{\alpha }<{\mathrm{\alpha }}_2,$$

30 FIG. 2 schematically illustrates an illustrative depiction of an effective photosensitive area for a microlens. FIG 34 _{n, m} was determined. The example of 30 schematically illustrates a state in which light rays passing through the microlens 34 _{n, m} were refracted and transmitted on a photosensitive surface 61r a group of photosensitive pixels. At both critical angles α ₁ and α ₂ , in the 30 are negative values. When positions in the main scanning direction x at which rays of light that are at critical angles α ₁ and α ₂ on a microlens 34 _{n, m} invade, on a photosensitive surface 61r arrive, with x ₁ and x ₂ are designated as in 30 shown are the arrival positions x ₁ and x ₂ in the main scanning direction x by - f _M x tanα ₁ respectively - f _M x tanα ₂ derived. Hereby designated f _M the focal length of the microlenses 34 _{n, m} , When the light receiving width of an effective photosensitive area in the main scanning direction x hp is used to satisfy the critical angles α ₁ and α ₂ the following comparison expression ( 8th ): $${\text{hp = f}}_{\text{M}}\times \left|\text{tan}{\mathrm{\alpha }}_2-\text{<figure-callout id="1" label="tan α" filenames="DE112017001126T5\_0032.png,DE112017001126T5\_0033.png" state="{{state}}">tan </figure-callout>}{\mathrm{\alpha }}_{}{\mathrm{}}_1\right|$$

If light rays with the angle of incidence γ equal to half the field angle of the rod lens 21 _n is on a microlens 34 _{n, m} invade, is the position of the light rays that are on the photosensitive surface 62r arrive, in the main scanning direction x equal f _M x tany. The following inequality (9) applies here: $$\text{hp}<2\times {\text{f}}_{\text{M}}\times \text{tan}\mathrm{\gamma }$$

From the above expressions ( 8th ) and ( 9 ) derives the following inequality (10): $$\left|\text{tan}{\mathrm{\alpha }}_2-\text{<figure-callout id="1" label="tan α" filenames="DE112017001126T5\_0032.png,DE112017001126T5\_0033.png" state="{{state}}">tan </figure-callout>}{\mathrm{\alpha }}_{}{\mathrm{}}_1\right|<2\times \text{tan}\mathrm{\gamma }$$

As will be described later, one group of photosensitive pixels is for each main beam passing through each of the rod lenses 21 _n passes through, into main light-sensitive pixels, which are multiple photosensitive pixels 62 which form an effective photosensitive area and subdivides photosensitive sub-pixels which are photosensitive pixels 62 which differs from the main light-sensitive pixels.

The image signal sensor 70 has a function of producing a captured image by constructing N field of view images representing N upright images of the same magnification as those of the rod lenses 211 to 21 _N are generated, and the N field of view images are combined. For each of the main rays passing through each of the rod lenses 21 _n passed through, the image signal processor selects 70 However, reception signals output from the main photosensitive pixels from reception signals output from a group of photosensitive pixels do not select reception signals output from photosensitive subpixels. Based on the selected receive signals, the image signal processor builds 70 an nth field of view image, that of the rod lens 21 _n equivalent.

The main photosensitive pixels and the photosensitive sub-pixels for each of the rod lenses 21 _n can be distinguished, the present embodiment can realize substantially similar functions as those of the fifth embodiment. That is, by selecting the main photosensitive pixels to coincide with an incident position of principal rays on the groups of photosensitive pixels of the imaging unit 61 match, it is possible to obtain a captured image in which a deterioration of the depth of field is prevented by superimposed areas of images between the rod lenses 21 _n and 21 _{n + 1} and between the rod lenses 21 _n and 21 _n-1 is caused.

Next, a configuration of the image signal processor will be described 70 with reference to the 31 and 32 described. 31 is a block diagram illustrating a configuration example of the image signal processor 70 of the sixth embodiment. 32 FIG. 10 is a flowchart illustrating an exemplary method of image processing of the sixth embodiment. FIG.

As in 31 shown, the image signal processor 70 The following: an image building device 71 based on raw or unprocessed image signals generated by the imaging unit 61 N field of view images are entered M ₁ to M _N builds; an image matching unit 72 having a shift amount D (i, j) between field of view images Mi and M _j detected by an image adjustment between adjacent field of view images Mi and M _j (j = i + 1) is executed; an image correction device 73 , which the field of view images M ₁ to M _N corrected by transfer magnifications τ ₁ to τ _N-1 of N-1 boundary areas in the field of view images M ₁ to M _N are estimated on the basis of the shift amount D (i, j) and each of the field of view images M ₁ to M _N using the transfer magnifications τ ₁ to τ _N-1 enlarged or reduced; and a composite image generator 74 who corrected the field of view images CM ₁ to CM _N combined to create a composite image and output the composite image as a captured image.

Here is the transfer magnification τ _i the transfer magnification in a boundary between the field of view images M _i and M _{i + 1} meant. The image correction device 73 For example, using the transfer magnifications τ _i to τ _N-1 in each case the field of view images M ₁ to M _N-1 correct, and the transfer magnification τ _N-1 can be used to view the field of view image M _N to correct. Alternatively, the image correction device 73 the transfer magnification by interpolation using a set of transfer magnifications τ _n and τ _{n + 1} or by using the transfer magnifications τ ₁ to τ _N-1 to calculate. In addition, it is possible to calculate a transfer magnification distribution that varies continuously such that the transfer magnifications at both ends of a field of view image M _n by using an interpolation of the transfer magnification, and to use this transfer magnification distribution for a correction of the field of view image. Even in the case where the transfer magnification τ _n-1 between the field of view pictures Mn _-1 and M _n and the transfer magnification τ _n between the field of view pictures M _n and Mn _{+ 1} Thus, a transfer magnification with a high accuracy can be used for a correction of the visual field images.

Referring to 32 receives the image building device 71 first a burst of digital received signals, the detection outputs from all the photosensitive pixels 62 at the imaging unit 61 as raw or unprocessed image signals and stores the raw or unprocessed image signals in an internal memory (step ST1 ). This raw or unprocessed image signal is obtained by scanning a scanned surface of a target object once 2 receive.

Next, the image build-up device 71 builds N-field images M ₁ to M _N which represent N upright images of the same magnification, respectively, from the rod lenses 211 to 21 _N be generated (step ST2 ). Specifically, when the nth field of view image M _n is built, the nth rod lens 21 _n corresponds, focuses the image building device 71 on groups of photosensitive pixels just below 3 × 13 microlenses ..., 34 _n-1 , ₆ . 34 _n , _-6 , ..., 34 _n , ₀ , ..., 34 _n , ₆ , 34 _{n + 1} , _-6 ( 27 ), the rod lens 21 _n and to this adjacent rod lenses 21 _n-1 and 21 _{n + 1} and selects the digital reception signals corresponding to the detection output of the main light-sensitive pixels having the effective light-sensitive areas for the main rays passing through the rod lens 21 _n have passed through from the digital reception signals corresponding to the detection output of these groups of photosensitive pixels. Here, the digital reception signals corresponding to the detection output of the photosensitive sub-pixels which do not have the effective light-sensitive areas for the main beams are not selected. Then build the image building device 71 the field of view image M _n based on the selected digital received signals.

wobei k_s,p ein Matrixelement in einer s-ten Zeile und einer p-ten Spalte der Matrix K ist, bei dem es sich um einen Wert von entweder „0“ oder „1“ handelt. Das Zeichen s bezeichnet eine Zeilenzahl, und p bezeichnet eine Spaltenzahl.More specifically, the image building apparatus 71 the nth field of view image M _n using a matrix K defined by the following mathematical formula (11): $$K=\left(k_{s.p}\right)$$

in which k _{s, p} is a matrix element in an s-th row and a p-th column of the matrix K, which is a value of either "0" or "1". The character s denotes a row number, and p denotes a column number.

The following mathematical formula is a first example of the matrix K: $$\begin{array}{l}K=\left[\begin{array}{lllllllllllllllllllllllllllllll}1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill \\ 0\hfill & 0\hfill & 0\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill \\ 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill \\ 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill \\ 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 0\hfill \\ 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 1\hfill & 1\hfill & 1\hfill \end{array}\begin{array}{ll}0\hfill & 0\hfill \\ 0\hfill & 0\hfill \\ 0\hfill & 0\hfill \\ 0\hfill & 0\hfill \\ 0\hfill & 0\hfill \\ 1\hfill & 1\hfill \end{array}\right]\\ \begin{array}{ccccc}p=-\mathrm{16\; ....}& & ...-101...& & \mathrm{....\; 1516}\\ m=-3...& ...6-6...& ...-101& ...6-6...& ...3\end{array}\end{array}$$

The number of lines s represents a number of 0 to 5 that everyone in 27 shown photosensitive pixels 62 is assigned. The number of columns p is a number from -16 to +16, which is the microlenses 34 _n-1 , _-3 to 34 _{n-1, 6,} 34 _n , _-6 to 34 _n . ₊₆ and 34n _{+ 1} . _-6 to 34n _{+ 1} , ₃ subservient below the rod lenses 21 _n-1 . 21n and 21 _{n + 1} is assigned. That is, p = -6 to +6 are the microlenses 34 _{n, -6} to 34n _{, +6} assigned directly below the rod lens 21 _n are located. The column numbers p = -16 to -7 are the microlenses 34 _{n-1, 3} to 34 _{n-1, 6} assigned directly below the to the rod lens 21n neighboring rod lens 21 _n-1 and p = +7 to +16 are the microlenses 34 _{n + 1} , _-6 to 34n _{+ 1} , ₃ just below the to the rod lens 21 _n neighboring rod lens 21 _{n + 1} assigned. A matrix element k _{s, p} corresponds to a s-th photosensitive pixel 62 immediately below a p-th microlens 34 and by it is meant a coefficient to be used for weighting the value of a pixel output (a luminance value) represented by a digital received signal corresponding to a detection output of the photosensitive pixel 62 equivalent.

It should be noted that a matrix element having a coefficient of "1" in the first example of the matrix K corresponds to a main photosensitive pixel and a matrix element having a coefficient of "0" corresponds to a photosensitive sub-pixel. In each of the case p = - 2 to 2 and s = 2 and 3, the case p = 3 to 7 and s = 3 and 4 and the case p = 12 . 13 and s = 4 . 5 For example, the width hp of a main photosensitive pixel may be 14 μm, which is equivalent to two pixels. Further, the width hp of a main photosensitive pixel in each of the case may be p = 8th to 11 and s = 4 and the case p = 14 to 16 and s = 5 on 7 μm, which is equivalent to a pixel. The limited angular range can be deduced from the above expression ( 8th ) be derived.

The luminance distribution of the nth field of view image M _n be Jn _{, p} , Jn _{, p} has 33 Values of the pixel number p (-16≤p≤16) for an n and is given by the following mathematical formula (12): $$J_{n.p}={\displaystyle {\Sigma }_{s=0}^5{k}_{s.p}}x{I}_{n.p.s}$$

This designates I _{n, p, s} the value of a pixel output corresponding to the number p of a microlens around the nth rod lens 21 _n around, and the pixel number s of a photosensitive pixel belonging to the microlens. When an assigned number of a microlens just below the nth rod lens 21 _n is denoted by m (-6≤m≤6) and a pixel number of a photosensitive pixel just below the microlens is denoted by s, an output of the photosensitive pixel becomes U _{n, m, s} designated. Here can I _{n, p, s} by the following expressions ( 13 ) are reproduced: $${\text{I}}_{\text{n}\text{, p}\text{, s}}=\{\begin{array}{ll}{\text{U}}_{\text{n}+\mathrm{1,}\text{m}=\text{p}-13\text{s}}\hfill & \left(7\le \text{p}\le 16\right)\hfill \\ {\text{U}}_{\text{n}.\text{m}=\text{p}.\text{s}}\hfill & \left(-6\le \text{p}\le 6\right)\hfill \\ {\text{U}}_{\text{n}-\mathrm{1,}\text{m}=\text{p}+13\text{s}}\hfill & \left(-16\le \text{p}\le -7\right)\hfill \end{array}$$

It should be noted that for U _{n, m, s} a value of m corresponds to a microlens. For I _{n, p, s} correspond to values of several combinations of {n, p} of a microlens. For example, if n = 0 and p = 0, is I _{n = 0, p = 0, s} = Uo, o, s. If n = 1 and p = -13, then I _{n = -1, p = 13, s} = U _{0,0, s} , and if n = -1 and p = 13 is is I _{n = -1, p = 13, s} = U _{0,0, s} , That is, when a figure is made with the variable p (-16≤p≤16) around the n = 0-th rod lens, a microlens is equivalent 34 _n , _m (n = 0, m = 0) three combinations of {n = 0, p = 0}, {n = 1, p = -13} and {n = -1, p = 13}.

Therefore, the image forming device 71 the field of view image M _n With 33 Pixel values of J _-16 to J16 per line in the main scanning direction x build up. Assuming that the number of pixels in the sub-scanning direction y equal P _y is, has the field of view image M _n 33 x P _y Pixels on.

It is to be noted that the range of the incident angle α ≦ -9 ° to + 9 ° in the above configuration example is the range of p = - 21 to +21 corresponds. Since the luminance value of the environment is low, in the first example for the matrix K, it is determined that luminance values in the ranges of - 21 ≤ p ≤ - 17 and 17 ≦ p ≦ 21 are not employed, but the present embodiment is not limited thereto. The number of lines of the matrix K can be increased. For example, a matrix K may be configured in which values of matrix elements s = 0 and p = -19, -18, -17 are equal to 1 and values of matrix elements s = 5 and p = 19, 18, 17 are equal to 1 ,

In the first example of the matrix K, the number of s is a matrix element of 1 is two if p = -13, -12, -7≤p≤7, and p = 12, 13, and the number of s with a matrix element of 1 is equal to one when -11≤p≤-8 and 8≤p≤11. This is to avoid mixing with an image produced by adjacent rod lenses. In order to improve the balance of the amount of light in comparison with the first example, as a second example of the matrix K, a matrix such as the following may be used. $$\begin{array}{l}K=\left[\begin{array}{lllllllllllllllllllllllllllllll}1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill \\ 0\hfill & 0\hfill & 0\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill \\ 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill \\ 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill \\ 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 0\hfill \\ 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 0\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill & 1\hfill \end{array}\begin{array}{ll}0\hfill & 0\hfill \\ 0\hfill & 0\hfill \\ 0\hfill & 0\hfill \\ 0\hfill & 0\hfill \\ 0\hfill & 0\hfill \\ 1\hfill & 1\hfill \end{array}\right]\\ \begin{array}{lllll}p=-\mathrm{16\; ....}\hfill & \hfill & ...-101...\hfill & \hfill & \mathrm{....\; 1516}\hfill \\ m=-3...\hfill & ...6-6...\hfill & ...-101\hfill & ...6-6...\hfill & ...3\hfill \end{array}\end{array}$$

After step ST2, the image matching unit performs 72 an image matching between the adjacent field of view images Mi and M _j and detects the shift amount D (i, j) between the field of view images Mi and M _j (Step ST3 ). In detail, the image matching unit 72 the pixel position of one of the adjacent field of view images Mi and M _j in the main scanning direction x and can detect, as the shift amount D (i, j), a shift amount at which the adjacent field of view images Mi and M _j agree with each other. Here, with the "shift amount at which the field of view images M _i and M _j to coincide with each other, "means a degree of shift in which the degree of similarity between the field of view images Mi and M _j is greatest. The degree of similarity can be determined, for example, using the sum-of-squared difference technique (SSD), the sum-of-absolute difference technique (SAD technique). or the Normalized Correlation Coefficient Technique (NCC) technique commonly used in image matching.

Next, the image correction device estimates 73 the transfer magnification τ _{i of} the boundary between the field of view images M _i and M _j on the basis of the detected shift amount D (i, j) using a look-up table prepared in advance (step ST4 ). In the lookup table is an estimated value of the transfer magnification τ _i stored corresponding to the shift amount D (i, j).

Next, the image correction device generates 73 corrected field of view images CM ₁ to CM _N , by the field of view images M ₁ to M _N using the transfer magnifications τ ₁ to τ _N-1 be corrected (step ST5 ). In detail, the image correction device 73 the field of view pictures M ₁ to M _N based on the transfer magnifications τ ₁ to τ _N-1 correct by taking each of the field of view images M ₁ to M _N with a Magnification of the reciprocal value of the transfer magnification is increased or decreased. As a method of enlarging or reducing the field of view image, for example, an image scaling technique may be used, such as a known bilinear interpolation method or a bicubic interpolation method. Then the composite image generator combines 74 the corrected field of view images CM ₁ to C M _N to create a composite image (step ST6 ). This composite image is output as the captured image.

Next, referring to 33 as well as on the 34A to 34I a simulation result of the image processing described. 33 Figure 5 is an illustration depicting an example of a document image displayed on a surface of a target object 2 is trained. In 33 For convenience of description, the main scanning direction is the same x and the sub-scanning direction y shown. The 34A to 34I are explanatory illustrations of simulation results of image processing. The 34A to 34C represent different images in the case of an accurate focusing (Δz = 0), the 34D to 34F represent different images in the case of defocusing (Δz = +0.6 mm), and the 34G to 34I represent different images in the case of defocusing (Δz = -0.6 mm).

Furthermore, each of the 34A . 34D and 34G an example of a raw or unprocessed captured image with a resolution of 3600 dpi in the main scanning direction x , That is, these captured images are images obtained by sequentially arranging the output signal U _{n, m, s} the photosensitive pixels obtained by the above expressions ( 13 ) is defined. As in 34A is shown at the time of accurate focusing with z = 0 a good image is obtained, however, as in the 34D and 34G is shown in the main scanning direction x Blurred image produced when Δz = 0.6 mm or Δz = -0.6 mm. The reason why these blurry images are created is because upright images are superimposed at the same magnification by three rod lenses.

On the other hand, each represents 34B . 34E and 34H three field of view images (resolution: 600 dpi), that of the three rod lenses 21 _n-1 . 21 _n and 21 _{n + 1} (R = -1, 0, +1) of the above configuration example. That is, these visual field images are formed by sequentially arranging the above Jn _{, p} achieved. For the convenience of explanation, a black line is inserted between the field of view images. The 34C . 34F and 34I are reference images showing the simulation results of an imaging system with a rod lens arrangement without the microlenses 34 represent.

Will the in the 34B . 34E and 34H shown images with the in the 34C . 34F and 34I The sharpness of the image differs significantly when Δz = ± 0.6 mm. The in the 34E and 34H displayed field of view images are better than those in the 34F and 34I shown pictures. This is because that in the 34F and 34I illustrated image blurring derives mainly from the fact that images are overlaid with different magnifications between adjacent rod lenses. For example, when Δz = 0.6 mm, a field of view image obtained from each of the rod lenses is an image that is in the main scanning direction x is reduced around the optical axis of the rod lens around. An image blur also occurs for a single rod lens, but an image shift due to the image reduction between adjacent rod lenses is greater than this. When Δz = -0.6 mm, in a similar manner, a field of view image obtained from each of the rod lenses is an image in the main scanning direction x is enlarged around the optical axis of the rod lens around.

In the present embodiment, a field of view image obtained from each of the rod lenses is converted into an image of the same magnification (step ST5 in FIG 32 ). Therefore, it is necessary to know to what extent a field of view image is reduced or enlarged. It should be noted that the transfer magnification can be uniquely determined when the document distance to the target object 2 is known. Although it is possible to separately use a distance sensor to obtain the document distance, the document distance can also be calculated for each of the rod lenses from a field of view image, as in FIGS 34B . 34E and 34H shown.

at 35A and 35B are results obtained by extracting field of view images with R = -1 and R = 0 from an image arranged without overlapping adjacent images when Δz = 0, as in FIG 34B and performing image matching processing (step ST3 ). 35B is shifted by Δ × 0 = 0.546 mm in the -x direction. Because the transfer magnification is the same 1 when Δz = 0, a shift amount that is exactly equivalent to 13 Pixels is (= 0.546 / 0.042), which is obtained by dividing Δ × 0 by the pitch of the microlenses. The 35C and 35D For example, in a similar manner, results obtained by extracting field of view images with R = -1 and R = 0 from an image arranged without overlapping adjacent images when Δz = -0.6 is how in 34H and performing image matching processing are obtained (step ST3). In 35D is a result for a shift by Δ × 1 in the -x direction. When Δz <0, the transfer magnification is larger than a magnification value 1 Thus, Δx1 is a value smaller than Δx0. In this way, the shift amount Δ × 1 is uniquely determined depending on the transfer magnification. The relationship between the shift amount and the transfer magnification can be calculated in advance or measured. Therefore, the transfer magnification of a field of view image can be obtained when the shift amount Δ × 1 is known (step ST4).

The image correction device 73 can obtain a corrected field of view image by enlarging or reducing the field of view image with the reciprocal of the obtained transfer magnification (step ST5). The composite image generator 74 can restore a sharp composite image by combining these corrected field of view images with the same magnification (step ST6 ). When the processes of the steps ST4 to ST6 For all field of view images, a good composite image can be obtained even for an image to be scanned whose document pitch is in the main scanning direction x changes. Furthermore, a good composite image can be obtained when the processes of the steps ST4 to ST6 also in the sub-scanning direction y be executed. For example, a sharp composite image may even be from a target object 2 such as a crumpled paper document or a book with a raised cover area.

As described above, the image signal processor is built 70 in the image capture device 1A According to the sixth embodiment, when the n-th visual image is built, the one through the n-th rod lens 21 _n represents the n-th field-of-view image based on received signals composed of a plurality of photosensitive pixels on the lower surfaces of the microlenses 34 _{n, -6} , ..., 34 _{n, 0} , ..., 34 _{n, 6} , the nth rod lens 21 _n are emitted from the main light-sensitive pixels without using reception signals output from the photosensitive subpixels. Therefore, it is possible to obtain a captured image which suppresses deterioration of the depth of field caused by superimposed areas of upright images with equal magnification between the rod lenses 21n and 21 _{n + 1} and between the rod lenses 21 _n and 21 _n-1 is caused.

In addition, the image signal processor performs 70 Image matching between adjacent field of view images to detect shift amounts between the field of view images (step ST3 ), and can correct the field of view images by using a transfer magnification corresponding to the detected shift amounts (steps ST4 and ST5 ). Therefore, the image signal processor 70 achieve an extremely sharp composite image (step ST6 ).

In this embodiment, the microlenses 34 the microlens array 33 a cylindrical lens surface having a non-zero curvature in the main scanning direction x on, like in 6 although not intended to be limited thereto. Instead of the microlens arrangement 33 can the microlens arrangement 33A used, which are the microlenses 34A which has a lens surface having a non-zero curvature both in the main scanning direction x as well as in the sub-scanning direction y have, as in 17 shown.

Furthermore, the rod lens arrangement 20 is used as an imaging optical system in the present embodiment, although it is not intended to be limited thereto. Instead of the rod lens arrangement 20 may be an imaging optical system having a plurality of refractive lenses as the imaging optical elements 50 be used as in the 18A and 18B shown.

In addition, the light source 11 , as in 22 shown on the same page as the rod lens arrangement 20 in relation to the target object 2 arranged. Another light source may be on the opposite side of the target object 2 be arranged such that the light passing through the surface of the target object to be scanned 2 is transmitted and scattered, in the rod lens arrangement 20 entry. This makes it possible to realize an image capturing device that generates a captured image similar to a bill reader used for ATMs based on transmitted scattered light.

Seventh embodiment

Next, a seventh embodiment according to the present invention will be described. 36 FIG. 10 is a block diagram showing a schematic configuration of an image signal processor. FIG 70A which is incorporated in an image sensing device of the seventh embodiment according to the present invention. A configuration of the image sensing device of the present embodiment is the same as those of the image capture device 1A of the sixth embodiment, except that the image signal processor 70A from 36 instead of the image signal processor 70 of the 22 and 29 is included.

The in 36 illustrated image signal processor 70A similar to the image signal processor 70 the first embodiment, an image forming apparatus 71 , an image matching unit 72 , an image correction device 73 and a composite image generator 74 on. The image signal processor 70A The present embodiment further includes: a distance calculating device 75 showing the document distance (the distance to a target object) in a border area of each of the field of view images M ₁ to M _N calculated on the basis of the shift amounts between the field of view images of adjacent rod lenses by the image matching unit 72 be estimated; and a state detector 76 that determines the state of the target object 2 detected on the basis of the calculated document distance.

37 FIG. 10 is a flowchart illustrating an exemplary method of image processing of the seventh embodiment. FIG. Referring to 37 lead the image building device 71 , the image matching unit 72 , the image correction device 73 as well as the composite image generator 74 the preceding steps ST1 to ST6 out. Using the shift amount D (i, i + 1 ), in the previous step ST3 is calculated, the distance calculation device refers 75 on a lookup table that was created in advance, and calculates each the document distance d ₁ to d _N-1 in boundary regions of the field of view images M ₁ to M _N (Step ST4 ). It should be noted that the document distance di from the transfer magnification τ _i of a boundary region, since there is a one-to-one relationship between the displacement amount D (i, i + 1) and the transfer magnification τ _{i of} each boundary region.

In the look-up table, an estimated value of the document distance corresponding to the shift amount D (i, i + 1) is stored. These document distances d ₁ to d _N-1 are delivered as a depth map. Because the transfer magnification of a field of view image, that of each of the rod lenses 21 _n is obtained, which corresponds to the document distance on a one-to-one basis, the document distance can be calculated from the shift amount.

Here, the spatial resolution in the main scanning direction (the x direction) of the depth map is the pitch Pr of the rod lens array 20 which is coarser than the pitch of the pixels. Therefore, the distance calculation device 75 a two-dimensional distribution (a distribution on an xy plane) of the document pitch as a depth map with a better accuracy than the pitch Pr of the rod lens array 20 by performing an interpolating process, such as interpolation.

Next, the state detector detects 76 the state of the target object 2 based on the document image in step ST4 is obtained (step ST8 ). The state detector 76 For example, the presence or absence of a protrusion or scratch in a strip or material of the target object 2 detect or can the degree of unevenness of the target object 2 detect. Alternatively, the state detector 76 the detection result as a result of a check of a surface to be scanned of the target object 2 submit. In particular, in the present embodiment, it is possible to distinguish very small bumps on a surface of a target object, and thus it is possible to check whether a bill, which is a target object, has a band attached thereto. Moreover, since it is possible to detect a mark of intaglio printing indicating unevenness formed on a bill along with its height, it contributes considerably to banknote authentication.

Although the various embodiments according to the present invention have been described with reference to the drawings, these embodiments are examples of the present invention, and thus various other forms than those embodiments may be employed.

In addition, any combinations of the first to seventh embodiments, modifications of any components in the respective embodiments, or omission of any components in the respective embodiments may be made within the scope of the present invention. For example, a combination of the second embodiment and the third embodiment may be performed, and a combination of the fourth embodiment and the fifth embodiment may be performed.

Industrial applicability

For example, since an image capturing device according to the present invention is capable of detecting an image formed on a surface of a target object such as a document with high accuracy, the image capturing device is suitable for use in a copier, an image scanner, a facsimile machine, a banknote reader and a surface inspection device. In the case where an image sensing device according to the present invention is applied to a surface inspection device, the image sensing device may be used to detect scratches, dirt, defects, hues on a surface of the target object, or the position of an object which is formed on the surface.

LIST OF REFERENCE NUMBERS

1, 1A

Image capture devices

2

target

10, 10A

Contact image sensor (CIS) units

11

light source

12, 12A

casing

20

Rod lens array

21 ₁ to 21 _N

rod lenses

30

sensor substrate

31, 31K, 61

Imaging units

31R

Line sensor for red

31G

Line sensor for green

31B

Line sensor for blue

31A, 31P

peripheral circuits

32r, 32g, 32b, 32x, 32xa, 62

photosensitive pixels

33, 33A

Microlens arrays

34, 34A

Micro condenser lenses

35, 35A

light-shielding structures

35s

openings

40, 40A

Image Signal Processors

50

Imaging optical elements

51 to 54

refractive lenses

70, 70A

Image Signal Processors

71

Image building apparatus

72

Image matching section

73

Image correction apparatus

74

Kompositbildgenerator

75

Distance calculating means

76

state detector

x

main scanning

y

Sub-scanning

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 6342131 [0002, 0004]

Claims (20)

Image capture device comprising: an imaging optical system comprising N imaging optical elements arranged along a main scanning direction set in advance, where N is an integer greater than or equal to 2, each of the N imaging optical elements being based on light which is scattered by a target object, produces an upright image with equal magnification; a microlens array comprising P micro-condenser lenses arranged along the main scanning direction at focal positions or focal points of the N-imaging optical elements, where P is an integer greater than N; and an imaging unit having P photosensitive pixels or P sets of groups of photosensitive pixels arranged at positions where light beams are concentrated by means of the microlens array and arranged to correspond respectively to the P micro-condensing lenses . wherein each of the micro-condenser lenses has a refractive power for focusing, from the light beams incident from the imaging optical system, the light beams incident at an angle of incidence within a limited angular range set in advance to positions which are different from positions incident on light rays incident at an angle of incidence outside the limited angle range, and wherein the P photosensitive pixels or the sets of photosensitive pixel groups have an effective photosensitive area which receives only the light rays incident on the principal rays passing through the N imaging optical elements which are incident on each at an angle of incidence within the limited angular range of the micro-condenser lenses. Image capture device according to Claim 1 , wherein a comparison expression is satisfied with $${\mathrm{\alpha }}_{\text{L}}=\text{arctan}\left[\text{Ha}/\left(2\times {\text{f}}_{\text{M}}\right)\right]<\mathrm{\beta }$$

where f _M denotes a focal length of each of the micro-condenser lenses, ha denotes a light-receiving width of the effective photosensitive area in the main scanning direction, β designates a half field angle of each of the image-forming optical elements in the main scanning direction, and α _L denotes a critical angle defines the limited angle range. Image capture device according to Claim 1 or 2 further comprising a light-shielding structure formed between the microlens array and the imaging unit, the light-shielding structure shielding a light beam incident on each of the micro-condenser lenses from an angle of incidence outside the limited angle range and is concentrated by each of the micro-condenser lenses. Image capture device according to one of Claims 1 to 3 , wherein a comparison expression is satisfied with $${\text{f}}_{\text{M}}\times \text{tan}\mathrm{\beta }<\text{Pt}-\text{Ha}/2$$

where f _M denotes a focal length of each of the micro-condenser lenses, β denotes a half field angle of each of the imaging optical elements in the main scanning direction, ha denotes a light-receiving width of the effective photosensitive area in the main scanning direction, and Pt denotes an arrangement pitch of Micro-condenser lenses in the main scanning direction. Image capture device according to one of Claims 1 to 3 , wherein a comparison expression is satisfied with $${\text{f}}_{\text{M}}\times \text{tan}\mathrm{\beta }<\text{Pt}/2$$

where f _M denotes a focal length of each of the micro-condenser lenses, β designates a half field-of-view angle of each of the imaging optical elements in the main scanning direction, and Pt denotes an arrangement pitch of the P micro-condenser lenses in the main scanning direction. Image capture device according to Claim 3 , - wherein the light-shielding structure has a plurality of openings formed to face the photosensitive pixels, respectively; and wherein the plurality of openings allow only the light rays incident at an angle of incidence within the limited angular range to pass through from the light rays incident on each of the micro-condenser lenses. Image capture device according to Claim 6 each of the P micro-condenser lenses has a cylindrical lens surface with a curvature in the main scanning direction; and wherein each of the openings forms a slot extending along an upper portion of the lens surface. Image capture device according to Claim 6 or 7 in which a positional shift amount of the P micro-condenser lenses is formed between a center of each of the openings and an optical axis of a micro-condenser lens that concentrates light beams on each of the openings in the main scanning direction; and wherein the positional displacement amount increases when each of the openings is located away from an optical axis of an imaging optical element corresponding to each of the openings of the N-imaging optical elements. Image capture device according to one of Claims 1 to 8th wherein each of the P micro-condenser lenses has a lens surface having a non-zero curvature both in the main scanning direction and in a direction orthogonal to the main scanning direction. Image capture device according to one of Claims 1 to 9 - wherein the imaging unit comprises a signal processing circuit to process outputs of the P photosensitive pixels or the P sets of photosensitive pixel groups; and wherein the signal processing circuit is disposed in a region disposed in a non-light-receiving region different from the effective light-sensitive region. Image capture device according to one of Claims 1 to 10 wherein the imaging optical system comprises a rod-lens array having N rod lenses as the N-imaging optical elements. Image capture device according to one of Claims 1 to 10 wherein the imaging optical system as the N-imaging optical elements comprises a group of refractive lenses for generating the upright image at the same magnification. Image capture device according to Claim 1 and further comprising an image signal processor for generating a captured image by constructing N field of view images representing an upright image of equal magnification produced by the N imaging optical elements and combining the N field of view images to thereby generate a captured image, the image signal processor having image forming means for selecting, for each principal ray passing through each of the imaging optical elements, the received signals output from the sets of photosensitive pixel sets which are output from a plurality of main photosensitive pixels contained in the effective photosensitive area, and to construct a field of view image corresponding to the N-field image forming optical element based on the selected received signals. Image capture device according to Claim 13 wherein the image signal processor comprises: an image matching unit to perform image matching between adjacent field of view images of the N field of view images and to detect shift amounts between the adjacent field of view images; an image corrector device to estimate transfer magnifications of the respective N field of view images on the basis of the detected shift amounts and to correct the N field of view images by enlarging or reducing each of the N field of view images using the estimated transfer magnifications becomes; and a composite image generator for producing a composite image by combining the corrected N-FOV images and outputting the composite image as the captured image. Image capture device according to Claim 14 wherein the image matching unit shifts a pixel position of one of the adjacent field of view images in the main scanning direction to detect as each of the shift amounts a shift amount at which the adjacent field of view images coincide with each other. Image capture device according to one of Claims 13 to 15 method further comprising: a distance calculating device for calculating a distance to the target object for each of the N field of view images on the basis of the transfer magnifications estimated by the image correcting device; and a state detector for detecting a state of the target based on the calculated distance. Image capture device according to one of Claims 13 to 16 wherein each of the P micro-condenser lenses has a cylindrical lens surface with a curvature in the main scanning direction. Image capture device according to one of Claims 13 to 17 wherein each of the P micro-condenser lenses has a lens surface having a non-zero curvature both in the main scanning direction and in a direction orthogonal to the main scanning direction. Image capture device according to one of Claims 13 to 18 wherein the imaging optical system comprises a rod lens arrangement having rod lenses as the imaging optical elements. Image capture device according to one of Claims 13 to 19 wherein the imaging optical system for generating the upright image at the same magnification comprises a group of refractive lenses as the imaging optical elements.

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